Systems, devices and methods for draining and analyzing bodily fluids

ABSTRACT

Systems, devices and methods for draining and analyzing bodily fluids are disclosed in which a drainage assembly is configured to prevent negative pressure build-up. The drainage assembly generally includes a catheter which may include a drainage lumen, a reservoir, a venting mechanism in fluid communication with the drainage lumen and a positive pressure lumen, and a controller. The venting mechanism may further include a valve which is configured to maintain a closed position, as well as a vent in fluid communication with the valve, where the venting mechanism is configured to inhibit wetting of the vent from fluid within the drainage lumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/277,957 filed Sep. 27 2016, which claims the benefit of priority toU.S. Provisional Application No. 62/256,257 filed Nov. 17, 2015 and U.S.Provisional Application No. 62/270,022 filed Dec. 20, 2015 and U.S.Provisional Application No. 62/270,623 filed Dec. 22 2015 and U.S.Provisional Application No. 62/275,348 filed Jan. 6, 2016 and U.S.Provisional Application No. 62/290,878 filed Feb. 3 2016 and U.S.Provisional Application No. 62/307,988 filed Mar. 14, 2016 and U.S.Provisional Application No. 62/317,746 filed Apr. 4, 2016 and U.S.Provisional Application No. 62/372,731 filed Aug. 9, 2016 and is relatedto PCT Application No. PCT/US2014/44565 filed Jun. 27, 2014, PCTApplication No. PCT/US2015/010530 filed Jan. 7, 2015, and PCTApplication No. PCT/US2015/52716 filed Sep. 28, 2015, each of which isincorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of medical devices, inparticular devices that aid emptying of the bladder, measure urineoutput and various urine parameters such as oxygen tension, urineconductance and urine specific gravity, monitor renal function, analyzeurine parameters, including urine content, including the presence ofinfection, and track and/or control fluid administration. The presentinvention further relates to medical devices capable of sensingphysiologic data based on sensors incorporated into a catheter adaptedto reside in any of a urinary tract, gastrointestinal tract, rectallocation, pre-peritoneal, pleural space or other body cavity.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if each suchindividual publication or patent application were specifically andindividually indicated to be so incorporated by reference.

BACKGROUND OF THE INVENTION

It is estimated that 10% of all hospitalized and long-term care patientsreceive an indwelling urethral catheter. Almost all critically illpatients receive one, and in the ICU it is routine procedure to monitorurine output every hour. The amount of urine produced is an indicator offluid status and renal function. However, numerous sources of error cancause erroneous measurements of this important indicator.

The most common device used to drain the bladder is the Foley catheter.Since its introduction, the design of a flexible tube with an anchoringballoon and eyelets that allow urine to drain through a central lumenhas remained largely unchanged. However, it has been found that thecurrent design of Foley catheters can result in a large residual volumeremaining in the bladder, for example greater than 50 mL in supinepatients. See Fallis, Wendy M. Indwelling Foley Catheters Is the CurrentDesign a Source of Erroneous Measurement of Urine Output? Critical CareNurse 25.2 (2005): 44-51. In one study, mean residual volume was 96 mLin the ICU and 136 mL in the general ward. See, Garcia et al.,Traditional Foley Drainage Systems—Do They Drain the Bladder?, J Urol.2007 January; 177(1):203-7; discussion 207. A large residual volume ofurine is also often found in the drain tube that connects the Foleycatheter to the drainage bag, or elsewhere in the drainage system.

The residual urine in the bladder and drain tube is a result of largeair bubbles (air locks) that are formed in the tube and prevent the flowof urine from the bladder to the drainage bag. As a result, it hasbecome routine procedure for nurses to manipulate the drainage tubeprior to measuring urinary output, which helps empty the tubing. In theICU, where measurements are made as often as every hour, this is a veryrepetitive and imprecise process. A need exists for more accurate andautomatic urine output measurement.

In addition, an opportunity exists, within the urine collection system,to measure and analyze urine parameters.

In addition to improving urine output measurement and urine parameteranalysis, the urine drainage catheter itself offers an untappedopportunity to detect, collect and analyze additional patientparameters.

In addition, many types of medical devices are designed to controltreatment and/or maintenance of a patient. For example, a respirator cancontrol patient respiration rate, volume, and/or gas mixture, amongother things. An IV (intravenous delivery) can deliver fluid and/orother substances, such as drugs, to a patient. Other devices includethose that can deliver drugs or perform other actions. These types ofmedical devices can be tightly controlled via various settings etc. Anurse or other practitioner may check various patient parameters andadjust the medical treatment device settings accordingly. A controllerwhich automatically or semi-automatically uses patient parameters tocontrol the settings of medical treatment devices is needed.

SUMMARY OF THE INVENTION

A Foley type catheter, widespread in use, having a low cost, and easilyput in place by health care professionals may be used as a vehicle forderiving critical diagnostic information, by modifying a Foley typecatheter, and/or by adding functionality to a Foley type catheter. Thetechnology disclosed herein provides for the delivery of highly resolvedand previously unavailable diagnostic information, as may be derivedfrom a Foley type catheter with intra-abdominal pressure (and other)sensing capability.

In addition, the development of air locks has been found tosignificantly skew intra-abdominal pressure readings. In addition, abladder which is not empty can also adversely affect pressure readingswithin the bladder. The technology disclosed herein also provides forthe detection and removal of air locks in the setting of intra-abdominalpressure measurements or otherwise, as well as more complete bladderdrainage.

The technology disclosed herein seeks to more effectively drain thebladder, prevent airlocks from forming in the drainage tube and clearingthem when they do, and increase the accuracy with which urine output ismeasured in an automated way. The disclosed technology also seeks toincorporate additional measurements of the urine, including oxygentension, conductance, and specific gravity, gas pressures, turbidity,infection, sediment and others to improve the monitoring of fluidstatus, renal function, and other important patient parameters.

The disclosed technology also relates to a Foley type catheter forsensing physiologic data from the bladder and/or urinary tract of apatient, the physiologic data particularly including those gathered byhigh fidelity pressure sensing and transduction into signals suitablefor processing. In some embodiments, the pressure-sensing Foley typecatheter may further be enabled to sense temperature and analytes ofclinical significance. Examples of physiological parameters that thesensing Foley catheter system may measure (time specific measurementsand trends of values over time) include: urine output, respiration rate,heart rate, heart rate variability, stroke volume, stroke volumevariability, intra-abdominal pressure (IAP), tissue oxygenation, tissuegas content, pulse transit time, pulmonary blood volume variability,temperature, blood content and other patient parameters

One embodiment of a drainage assembly which is configured to preventnegative pressure build-up may generally comprise an elongate catheterhaving a first end configured for insertion within a body lumen. Thecatheter may have at least one opening near or at the first end in fluidcommunication with a catheter lumen defined therethrough, a drainagelumen in fluid communication with a second end of the catheter, areservoir in fluid communication with the drainage lumen, and a ventingmechanism in fluid communication with the drainage lumen and a positivepressure lumen. A valve may be positioned within the venting mechanismand configured to maintain a closed position until a first pressurelevel within the drainage lumen drops to a second pressure level suchthat the valve moves to an open position. Also, a vent may be positionedin fluid communication with the valve, wherein the venting mechanism isconfigured to inhibit wetting of the vent from fluid within the drainagelumen; and a controller in communication with the reservoir, wherein thecontroller is configured to determine a fluid volume collected withinthe reservoir.

In another embodiment, the drainage assembly may be configured toprevent negative pressure build-up, generally comprising an elongatecatheter having a first end configured for insertion within a bodylumen, the catheter having at least one opening near or at the first endin fluid communication with a catheter lumen defined therethrough. Adrainage lumen may be in fluid communication with a second end of thecatheter, a positive pressure lumen in fluid communication with thedrainage lumen, a reservoir in fluid communication with the drainagelumen, and a venting mechanism coupled to the drainage lumen, whereinthe venting mechanism is configured to inhibit wetting of a vent from afluid within the drainage lumen. A controller may be in communicationwith the reservoir, wherein the controller is configured to determine afluid volume collected within the reservoir, and a valve may also beincluded which is configurable between a closed position and an openposition, wherein the valve moves from the closed position to the openposition when a first pressure level imparted upon the valve drops to asecond pressure level.

Certain patient parameters which may be measured and/or determined bythe disclosed technology are impacted by, and/or impact, a patient'streatment by medical treatment devices. For example, a patient's urineoutput, respiration rate, heart rate, stroke volume, stroke volumevariability, intra-abdominal pressure (TAP), tissue oxygenation, tissuegas content, temperature, blood content and other patient parameters maybe impacted by, and/or impact, medical treatment. Some examples ofmedical treatments, which may be controlled by medical devices includerespiration rate and content, controlled by respirators, IV rate andcontent controlled by an IV drip controller, drug delivery controlled bya drug delivery device or IV controller, urine output controlled by aurine output pump, abdominal fluid volume controlled by drain pumps, andother treatments controlled by other medical treatment devices.

One embodiment of a system for analyzing bodily fluids may generallycomprise an elongated catheter having an expandable balloon positionednear or at a distal end of the catheter and further defining one or moreopenings in proximity to the balloon, a venting mechanism coupled to aproximal end of the catheter, the venting mechanism configured to passair therethrough when negative pressure is applied to the ventingmechanism, a first lumen coupled to the venting mechanism and in fluidcommunication with the one or more openings, a second lumen in fluidcommunication with the balloon, a reservoir coupled to a proximal end ofthe first lumen and in fluid communication with the one or moreopenings, and a controller which is configured to connect to thereservoir and is programmed to control a pressure within the firstlumen, wherein the controller is further programmed to monitor a urineoutput received in the reservoir from a patient and determine anintra-abdominal pressure of the patient based in part upon changes inpressure within the balloon, and wherein the controller is furtherconfigured to store patient data.

In one exemplary method for analyzing one or more body parameters from apatient, the method may generally comprise positioning an elongatedcatheter having an expandable balloon positioned near or at a distal endof the catheter within a body lumen filled at least partially with abody fluid, receiving the urine through one or more openings definedalong the catheter in proximity to the balloon, further receiving thebody fluid within a reservoir located external to the body lumen andwhich is in fluid communication with the one or more openings via afluid lumen, venting air through a venting mechanism which is incommunication with the fluid lumen when negative pressure is applied tothe fluid lumen, analyzing a volume of the urine received within thereservoir via a controller which is programmed to control the negativepressure to the venting mechanism, determining an intra-abdominalpressure of the patient based in part upon the changes in pressurewithin the balloon, and storing one or more parameters of patient datavia the controller.

Some embodiments of the sensing Foley catheter system include a loopcontroller which receives one or more pieces of data relating to patientparameters, and uses this information to control one or more medicaltreatment device or devices. The loop controller may be integrated witheither the device measuring the patient parameter, or the medicaltreatment device, or both.

A pressure measuring balloon on a catheter, such as that disclosed ininternational patent application number PCT/US14/44565, titled SensingFoley Catheter (which is herein incorporated by reference in itsentirety) is an example of a device which measures patient parameters.Additional embodiments are disclosed herein. A sensing Foley cathetersystem, may include a pressure measuring balloon and/or other sensors,as well as the ability to measure urine output and content to determinepatient parameters such as urine output rate, IAP, respiratory rate,heart rate, stroke volume, tissue oxygenation, urine composition,temperature and other patient parameters.

Other parameters that may be measured and/or determined via a SensingFoley type Catheter include urine specific gravity and pulse pressurevariability. These parameters may be used to help control a medicaltreatment device such as a ventilator and/or infusion and/or hydratingdevice.

Urine specific gravity is a measure of the number and weight of soluteparticles in urine. Normal ranges are around 1.010 to 1.030.Measurements that are higher than this may indicate dehydration or otherconditions. Measurements that are lower than this may indicate fluidoverload or other conditions. Measurements may be done by sensors on aSensing Foley Catheter. Measurement results may indicate increasing (inthe case of dehydration) or decreasing (in the case of fluid overload)the infusion rate for a patient. Measurement results may also indicate achange in ventilation parameters or drug infusions etc.

Pulse pressure variability can be a predictor of fluid responsiveness toa medical treatment device such as a ventilator and/or fluid infusiondevice. A Sensing Foley Catheter can record a pressure waveform and thecontroller can identify the maximum and minimum pressure pulses, whichcoincide with the respiration cycle. The controller can calculate pulsepressure variability. Pulse pressure variability can help determinewhether a given patient will or will not respond to fluid therapy. Pulsepressure variability can also be used by the controller to controltherapy in a feedback loop. If pulse pressure variability is high, morefluid may be required by the patient. If pulse pressure variability islow, less fluid may be required.

A Sensing Foley catheter system can measure cardiac activity viapressure sensing in the bladder. Because a Sensing Foley Catheter iscapable of measuring respiratory activity as well as cardiac activity,and the frequency of the respiratory rate and the cardiac rate of apatient can be similar to each other, a patient's respiratorymeasurements can distort the cardiac measurements. To overcome thisissue, some embodiments of a controller may pause the respirator at theend of one or more inspiration points, and/or pause the respirator atthe end of one or more expiration points (for just a few seconds eachtime, for example 1 to 3 seconds, or for example, 1 to 4 seconds) sothat the cardiac waveform can be captured without respiratorydistortion. Capturing detailed cardiac waveforms in this manner allowsthe controller to determine stroke volume variability (SVV) which isuseful in the detection of sepsis and the prevention of fluid overload.As an alternative embodiment, the patient may be asked to hold his/herbreath at an inspiration point and/or an expiration point.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth. A betterunderstanding of the features and advantages of the present inventionwill be obtained by reference to the following detailed description thatsets forth illustrative embodiments, in which the principles of theinvention are utilized, and the accompanying drawings of which:

FIG. 1 shows an embodiment of a sensing Foley type catheter.

FIG. 2 shows an example of respiratory rate sensing data.

FIG. 3 shows a detailed portion of a respiratory profile.

FIG. 4 shows an example of cardiac rate and relative cardiac outputsensing data.

FIG. 5 shows data related to relative cardiac output sensing in a humanleg raising exercise.

FIG. 6 shows an example of peritoneal sensing data.

FIG. 7 shows an example of peritoneal sensing data.

FIG. 8 shows the relationship among intraabdominal pressure, respiratorywave pressure, and cardiac pressure.

FIG. 9 provides a flow diagram of an embodiment of the method.

FIG. 10A shows an embodiment of the sensing Foley catheter system.

FIG. 10B shows a detail view of airlock clearing mechanism and fluidcollection & analysis system of FIG. 10A.

FIG. 10C shows the disposable components of an embodiment of the sensingFoley catheter system.

FIG. 11 shows another embodiment of the sensing Foley catheter system.

FIG. 12 shows another embodiment of the sensing Foley catheter system.

FIG. 13 shows another embodiment of the sensing Foley catheter system.

FIGS. 14A and B show an embodiment of a collapsible drainage tube thatresides in a kink-resistant tube.

FIG. 15 shows an example of a clearing mechanism of the sensing Foleycatheter system.

FIG. 16 shows an example of a clearing mechanism of the sensing Foleycatheter system.

FIG. 17 shows an embodiment of the sensing Foley catheter system with adrainage tube with a gas-sampling lumen.

FIG. 18 shows an active vented system with a vent and pump.

FIG. 19 illustrates an embodiment of the sensing Foley catheter systemwith additional vents for pressure relief and sterility.

FIG. 20 illustrates an embodiment of the sensing Foley catheter systemwith a pressure relief vent and relief valve.

FIG. 21 shows an embodiment of a collection vessel, chamber or cassettewhich may be included in the sensing Foley catheter system to detectbacteria, blood and/other substances in the urine using UV/lightspectroscopy.

FIG. 22 shows the various absorption wavelengths of E. coli, red bloodcells, and plasma in urine to light.

FIG. 23 shows an embodiment of the cassette which includes baffle orflap.

FIGS. 24 and 25 show graphs representing pressure balloon primingmethods in some embodiments.

FIG. 26-28 show flow charts of possible logic in various embodiments ofthe invention.

FIG. 29 shows an embodiment of the sensing Foley catheter system with aloop controller in a patient environment.

FIG. 30 shows an embodiment of the sensing Foley catheter system with aloop controller in a patient environment.

FIG. 31 shows an embodiment of the sensing Foley catheter system with aloop controller in a patient environment.

FIG. 32 shows an embodiment of the sensing Foley catheter system with aloop controller in a patient environment.

FIG. 33 shows details of a loop controller with possible inputparameters and output actions.

FIG. 34 is a plot of ultrasonic and pressure measurements of volumedivergence.

FIG. 35 shows the distal end of an embodiment of the sensing Foleycatheter.

FIG. 36 shows an embodiment of a filter within a balloon.

FIG. 37 shows an embodiment of a filter within a balloon with theballoon inflated.

FIG. 38 shows an embodiment of a filter within a balloon with theballoon deflated.

FIG. 39 shows an embodiment of a filter within a balloon.

FIG. 40 shows an embodiment of a filter within a balloon.

FIG. 41 shows an embodiment of a filter within a balloon.

FIG. 42 shows an embodiment of a filter within a balloon.

FIG. 43 shows an embodiment of a filter within a balloon.

FIG. 44 shows an embodiment of a filter within a balloon.

FIG. 45 shows an embodiment of a filter within a balloon.

FIG. 46 shows an embodiment of a filter within a balloon.

FIG. 47 shows an embodiment of a balloon with multiple access lumens.

FIGS. 48 and 49 show embodiments of a balloon.

FIGS. 50-53 show various embodiments of a balloon catheter with an gaspermeable membrane.

FIG. 54 shows a controller for measuring gas content via a ballooncatheter.

FIGS. 55 and 56 are schematic diagram of gas measuringcatheter/controller systems.

FIGS. 57A and 57B show embodiments of a gas measuring add-on component.

FIG. 58A shows a table that lists combinations of parameters that allowfor possible signatures for identifying Acute Kidney Injury and UTIbased on patient parameters.

FIG. 58B shows a table that lists combinations of parameters that allowfor possible signatures for identifying Acute Kidney Injury, sepsis, andacute respiratory distress syndrome, based on patient parameters.

FIG. 59 shows a pressure signature curve within the collection chamberduring clearance of an air-lock.

FIG. 60 is a block diagram of a data processing system, which may beused with any embodiments of the invention.

FIG. 61 shows alternative wavelengths that can be used to identify redblood cells, and/or plasma/white blood cells.

FIG. 62 shows urine output data immediately following the administeringof a diuretic.

FIGS. 63A-B show how a smaller diameter lumen can compare to a largerdiameter lumen in the vent/filter area.

FIG. 64 shows a curved barb area.

FIG. 65 shows an embodiment of the sensing Foley catheter system with avent tube.

FIG. 66 shows the sensing Foley catheter system with a separate positivepressure vent tube.

FIG. 67 shows a magnification of the barb area of FIG. 66.

FIGS. 68-86 show the barb area of various embodiments of the sensingFoley catheter system.

FIG. 87 shows an embodiment of the sensing Foley catheter system with aninternal vent tube.

FIG. 88 shows an embodiment of the sensing Foley catheter system with aninternal vent tube.

FIG. 89 shows an embodiment of the sensing Foley catheter system with aninternal vent tube and a positive pressure tube.

FIG. 90 shows an embodiment of the sensing Foley catheter system with aninternal vent tube.

FIG. 91 shows an embodiment of the sensing Foley catheter system with aninternal vent tube.

FIGS. 92A and 92B show some embodiments of the drainage lumen.

FIGS. 93A through 93E show another embodiment of the drainage lumen

FIGS. 94A-94C show embodiments of the sensing Foley catheter systemwhere the pressure sensor is on a separate catheter.

FIGS. 95A-C show embodiments of the sensing Foley catheter system withbubble reduction mechanisms.

FIGS. 96A-D show embodiments of the sensing Foley catheter system withbubble reduction mechanisms.

FIGS. 97A-D show embodiments of the sensing Foley catheter system withbubble reduction mechanisms.

FIGS. 98A-D show embodiments of the sensing Foley catheter system withbubble reduction mechanisms.

FIGS. 99A-C show embodiments of the sensing Foley catheter system withbubble reduction mechanisms.

FIGS. 100A-C show embodiments of the sensing Foley catheter system withbubble reduction mechanisms.

FIGS. 101A and 101B show embodiments of the sensing Foley cathetersystem with bubble reduction mechanisms.

FIG. 102 shows a pressure waveform and its extinction using a pressureballoon.

FIG. 103 shows sample clinical data illustrating a method of removingnoise from cardiac signals using ECG.

FIG. 104 shows sample clinical data illustrating stroke volumevariability analysis using a model waveform.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiments of the present invention are described indetail herein. However, alternative embodiments of various features ofthe device are also possible. Examples of these embodiments are providedbelow, but the scope of the invention is not limited to these specificconfigurations.

Sensing Foley Catheter

FIG. 1 shows an embodiment of a sensing Foley catheter and several ofits features. A catheter may be understood to have various sectionsaccording to its disposition when the catheter has been inserted into ahuman subject, such as a proximal portion that remains external to thesubject, a central or urethra-residing portion, and a distal or urinarybladder-residing portion.

Various internal lumens traverse the length of the catheter, such as anair or fluid lumen that communicates with a bladder retention balloon104 and a retention balloon port 118. A urine drainage lumen has adistal opening or openings 106 that resides in the bladder portion ofthe catheter, and has an opening at the proximal end 114 of thecatheter. The urine drainage lumen may be connected to a urine drainagetube that conveys the urine to a collecting receptacle. The urinedrainage tube may be separate from, or integral with, the sensing Foleycatheter. In some embodiments, the drainage lumen and distal opening inthe bladder may also serve as an infusion conduit by which medicinalagents may be infused, or through which heating or cooling fluid may beinfused. Analyte sensor(s) (not shown) or temperature sensor(s) (notshown) may be disposed on the catheter, either on the urethral portionor the bladder-residing portion of the catheter. Electrical or opticalfiber leads may be disposed in a lumen that allows communication ofsensing signals between distally disposed sensors and the proximalportion of the catheter, and then further communication to a dataprocessing apparatus or controller.

An inflatable pressure-sensing balloon 108 (or a pressure sensingmembrane arranged across an opening) may be positioned at or near thedistal end of the catheter. Embodiments of a pressure-sensing balloon orpressure sensing membrane may be understood as comprising a pressureinterface having a distal-facing surface exposed to pressure from withinthe bladder, and a proximal-facing surface exposed to a proximal fluidcolumn. The pressure-sensing balloon or membrane is in fluidcommunication with a fluid column or lumen which is in fluidcommunication with a pressure port 116 at or near the proximal end ofthe catheter. Embodiments of the fluid column (filled with a fluid,either liquid or gas) may comprise a dedicated lumen, or a shared lumen.

In some embodiments, a temperature sensor may exist at or near thedistal end of the catheter. Temperature port 110 may include temperaturecommunication wire 112 which connects the temperature sensor to adisplay, connector and/or controller.

Note that although FIG. 1 shows the proximal end of the cathetercomprising multiple separate ports, some or all of the ports may beintegrated into a single port, or integrated into a urine drainage linewhich travels to a urine drainage system and/or controller. Other lumensand/or ports may also exist.

Pressure-based physiologic parameters that the sensing Foley cathetersystem may sense, and/or determine via a controller based on the sensedparameters, may include, by way of example, peritoneal pressure,respiratory rate, and cardiac rate, relative pulmonary tidal volumeprofile, cardiac output, relative cardiac output, and absolute cardiacstroke volume. Some embodiments of the Foley type catheter may befurther equipped with any of a temperature sensor, one or more analytesensors, electrodes, and paired light sources and sensors. Embodimentsthus further equipped are capable of delivering other forms ofphysiologic data, as for example, blood pressure, oxygen saturation,pulse oximetry, EKG, and capillary fill pressure.

Embodiments of the sensing Foley catheter may be able to sense any oneor more of a plurality of clinically relevant parameters, such asincluded in the following examples: urine pH, urine oxygen content,urine nitrate content, respiratory rate, heart rate, perfusion pressureof the bladder wall or the urethral wall, temperature inside the bladderor the urethra, electro-cardiography via sensors on the bladder wall orthe urethra, respiratory volume, respiratory pressure, peritonealpressure, urine glucose, blood glucose via urethral mucosa and/orbladder mucosa, urine proteins, urine hemoglobin, blood pressure. Insome embodiments, the catheter can sense multiple parameters, but someembodiments may be limited to as few as a single parameter for focusedapplications (for example, respiratory rate in a patient in respiratorydistress).

The disclosed technology captures a high-resolution chronologicalprofile (pressure as a function of time) of peritoneal pressure fromwithin the bladder that can be transduced and processed into distinctpressure profiles assignable to particular physiologic sources,including peritoneal pressure, respiratory rate, and cardiac rate. Bytracking the pressure profile at a sufficiently rapid sampling rate, asprovided by the technology, the pressure profile can be furtherresolved, and/or analyzed, into relative pulmonary tidal volume, cardiacoutput, relative cardiac output, and absolute cardiac stroke volume.

Accordingly, aspects of the disclosed technology relate to fidelity andresolution of a pressure signal generated in response to changes inpressure within the bladder, such changes being reflective of a pressureprofile within the peritoneal cavity, such pressure profile includingcumulative input from the aforementioned physiologic sources. Aspects ofthe technology further relate to fidelity and resolution of thetransduction of the pressure signal into a highly resolvable electricalsignal. Aspects of the technology relate still further to processing thetotality of the electrical signal profile, a surrogate for the pressureprofile within the peritoneal cavity, into component profiles that canbe assigned to the physiologic sources.

The sensitivity of an inflated balloon as a pressure sensor is afunction, in part, of the pressure differential across the balloonmembrane as a baseline condition. The balloon has the greatestsensitivity to pressure when the baseline pressure differential is nearzero. As the baseline pressure differential increases, the sensitivityof the pressure-sensing balloon degrades. Accordingly, the disclosedtechnology provides an automatic priming method that maintains theballoon in an inflated state, but with a minimal pressure differential.

To effectively capture physiologic pressure profiles, the profiles needto be sampled at a rate that is sufficient to resolve the inherentfrequency of changes in the profile. This consideration is informed bythe Nyquist-Shannon sampling theorem, which states that a samplingfrequency of at least 2B samples/second is required to resolve an eventthat runs at a frequency of B cycles/second. As applied to a physiologicpressure cycle, for example, a cardiac rate of 70 beats/minute requiresa sampling rate of at least 140 samples/minute to effectively capturethe cycle. This relationship underlies aspects of the disclosedtechnology that specify the sampling rate particularly required tocapture physiologic pressure cycles such as relative pulmonary tidalvolume, cardiac output, relative cardiac output, and absolute cardiacstroke volume.

Embodiments of the technology include a pressure interface as may berepresented by a balloon having either a compliant membrane or anon-compliant membrane.

Expandable pressure sensing balloons, per embodiments of the technology,may assume one or more of at least two basic forms, compliant ornon-compliant. In compliant balloon types, which may be generallylikened to a conventional party balloon, the pressure-sensing balloon isformed from or includes a compliant membrane. Accordingly, the surfacearea of the membrane expands or contracts as a function of the expansionof the balloon. The compliance of the membrane determines variousfeatures of the balloon, as a whole, at different levels of expansion.Upon expansion, the balloon, if unconstrained, maintains a substantiallyconstant or preferred form or shape, as determined by the mandrel uponwhich the balloon is formed. Upon expansion of the balloon from aminimal volume to its maximal volume, the membrane of the balloonmaintains a level of tautness. Within the limits of compliance of thecompliant membrane, an increase in pressure during inflation results ina consequent expansion of volume. The balloon, on the whole may beconsidered partially compliant in that its shape responds to spatialconstraints that it may encounter upon expansion or inflation, howeverthe balloon does have a preferred or native shape, and such shapepreference prevents a level of shape compliance or conformability suchas that exhibited by a non-compliant balloon.

In a non-compliant balloon, the expandable pressure-sensing balloon isformed from or includes a non-compliant membrane, or a membrane that issubstantially non-compliant. Accordingly, the surface area of themembrane does not expand or contract in accordance with the level ofballoon expansion/pressurization. Non-compliant pressure-sensingballoons may be generally likened to a conventional Mylar® balloon. Thelack of compliance of the membrane determines various features of theballoon, as a whole, at different levels of expansion. Upon expansion ofthe balloon from a minimal volume to a level near its maximal volume,the membrane of the balloon is supple, and has a level of slackness.Expansion of a non-compliant balloon occurs by way of outwardly directedsmoothing of wrinkles and folds in the membrane. Deflation orcompression of a non-compliant balloon occurs by way of generallyinwardly directed wrinkling and infolding. When a non-compliant balloonis fully inflated (or substantially inflated) without being in aconfining space, it assumes a preferred or native shape as determined bythe geometry of the membrane or fabric of the balloon. However, in astate of partial inflation, the balloon, as a whole, is highly suppleand conformable, broadly taking the shape as may be dictated by aconfining space.

Expandable pressure sensing balloons, per embodiments of the technology,may also include features of both of the two basic forms, compliant andnon-compliant. In these embodiments, the membrane may include regionsthat are compliant and regions that are non-compliant. A balloon of thishybrid type would, as a whole, behave in a manner drawing frombehavioral aspects of both compliant and non-compliant balloons, asdescribed above. Further, compliant balloons may be formed with amembrane that is not of a homogeneous composition or thickness. In suchembodiments, regions of different thickness or composition could havevarying degrees of compliance, thus affecting the behavior of theseregions during expansion of the balloon. In still other embodiments,compliance of the membrane may have a bias or polarity that tends topermit compliance in one or more directions, and tends to disallowcompliance in one or more other directions.

Embodiments of the sensing Foley catheter include a device utilizing avery small pressure lumen for air transmission. Pressure readings usinginner lumen diameters of 3 mm, 1 mm, and 0.5 mm have been measured.Little degradation of the signal was seen when the air lumen diameterwas decreased from 3 mm to 1 mm and 0.5 mm.

These data indicate the appropriateness of using the embodiment of thepressure transduction system in a small diameter pediatric catheter downto a size as small as 4F. In this embodiment, as well, the tip of thecatheter can be lower profile than the rest of the catheter to allow fora consistently small diameter even with addition of the pressure sensingballoon. Thus, the catheter of the present invention is uniquely suitedto the pediatric indication where there is a dire need for moreappropriate, less invasive monitoring methods. In another embodiment,the retention balloon itself can be used as the pressure balloon, inorder to minimize the number of required lumens. In one embodiment, theretention balloon is used in its fully inflated state, and is only usedto track macro trends in IAP. In another embodiment, the retentionballoon is only slightly inflated in order to increase balloonsensitivity to small changes in pressure. This embodiment allows forfiner measurements of micro parameters, such as heart rate, relativestroke volume, relative cardiac output, respiratory rate, and relativetidal volume. A smaller pressure lumen also allows for more space in alarger catheter for other technologies, such as sensors etc.

In embodiments of the sensing Foley catheter where the retention balloonis used as the pressure balloon, the pressure measured within theretention balloon is offset by the pressure required to just inflate theballoon large enough for it to serve as a retention balloon. As aresult, the inflation pressure, and possibly the pressure resulting fromthe retention balloon being in contact with the inner surface of thebladder, needs to be subtracted from the pressure reading. In this way,smaller pressure changes may be tracked similarly to those measured bythe separate pressure balloon. The inflation pressure offset may bedetermined by measuring the pressure within the retention balloon whenit is first inserted into the patient, or by measuring the retentionballoon inflation pressure outside the patient, or by other means. Theretention balloon may be filled with fluid, air or any other appropriategas.

Embodiments of the disclosed technology may include embodiments in whichthe pressure sensor is a mechanical pressure sensor, such as those usingfiberoptic, strain gage, magnetic, resonant, and/or other suitabletechnologies.

FIG. 2 shows an example of respiratory rate sensing data from a humansubject, as provided by an embodiment of the sensing Foley cathetersystem. During this test period, the subject performs a respiratorysequence as follows: (1) breath being held at the end of an expiration,(2) valsalva, (3) hyperventilation, (4) valsalva, and (5) breath beingheld at the end of an expiration.

FIG. 3 shows a detailed portion of the normal respiration period in arespiratory profile similar to that shown in FIG. 2. Note that thepressure curve clearly shows the respiratory peaks, and thereforerespiratory rate can be determined, and heart rate peaks, and thereforeheart rate can be determined.

FIG. 4 shows an example of cardiac rate and relative cardiac outputsensing data from a human subject, as provided by an embodiment of thesensing Foley catheter system, and an EKG trace as measuredsimultaneously and independently. This graph clearly shows that theheart rate peaks as measured by the sensing Foley catheter are alignedwith the heart rate.

FIG. 5 shows data related to relative cardiac output sensing in a humanleg raising exercise in which cardiac output increases, as demonstratedby an increased amplitude of the cardiac pulse.

The data shown in FIGS. 6 and 7 were derived from studies done withYorkshire pigs under IACUC-approved protocols. FIG. 6 shows an exampleof peritoneal sensing data, with a focus on respiratory rate from a pig,as provided by an embodiment of the sensing Foley catheter system. FIG.7 shows an example of pig study that demonstrates the capability of anembodiment of the sensing Foley catheter system to detectintra-abdominal hypertension. In this study, the peritoneal cavity wasaccessed with a 5 mm Tenamian trocar. The trocar was then attached to a5 L bag of Lactated Ringers solution via a peristaltic pump, and thesolution was infused at a rate of about 1 L per minute. Fluid flow wasdiscontinued once a pressure of about 20 mmHg was obtained after whichthere was no net fluid flow in or out of the cavity.

FIG. 8 shows intraabdominal pressure, respiratory wave pressure, andcardiac pressure schematically arrayed as a two dimensional plot ofpressure (mm Hg on a logarithmic scale) vs. frequency (Hz). It can beseen that there is an inverse relationship between pressure andfrequency, and the various physiologic pressure-related parametersoccupy distinct sectors when arrayed in this manner. It is by thedistinctness of both these pressure and/or frequency profiles thatembodiments of the method, as disclosed herein, can resolve a singleoverall chronological pressure profile into the distinct subprofiles, inaccordance with their physiologic origin. Intra-abdominal pressuremeasurements may be resolved in the frequency range of about 0 Hz toabout 0.5 Hz. Respiratory pressure measurements may be resolved in thefrequency range of about 0.25 Hz to about 0.75 Hz. Cardiac pressuremeasurements may be resolved in the frequency range of about 0.75 Hz toabout 3.0 Hz. Intra-abdominal pressure measurements may be resolved inthe amplitude range of about 5 mm Hg to about 30 mm Hg. Respiratorypressure measurements may be resolved in the amplitude range of about0.5 mm Hg to about 5 mm Hg. Cardiac pressure measurements may beresolved in the amplitude range of about 0 mm Hg to about 0.5 mm Hg.Sampling frequencies—the frequency with which pressure measurements aretaken—are preferably about twice that of the resolution frequency. Forexample, sampling frequency may be about 0 Hz-1 Hz for intra-abdominalpressure measurements, 0.5 Hz-1.5 Hz for respiratory pressuremeasurements, and 1.5 Hz-6 Hz for cardiac pressure measurements.

FIG. 9 provides a flow diagram of an embodiment of the method ofmonitoring pressure as it occurs dynamically as waves of variedfrequency and amplitude in the intraabdominal cavity, as detected fromwithin the urinary bladder. Through the agency of a pressure interface,a high fidelity pressure profile is generated and transmitted proximallythrough a fluid column. More proximally, a pressure transducer convertsthe high fidelity pressure wave into a high fidelity electrical signalthat is informative of pressure frequency and amplitude. The generatedhigh fidelity electrical signal is then processed by a controller toyield data subsets that are reflective of components within the overallpressure profile, such subsets being attributable to particularphysiologic sources, such as peritoneal pressure, respiratory rate,cardiac rate, relative cardiac output, and patient motion or activity.

Sensing Foley Catheter System

FIG. 10A shows an embodiment of the sensing Foley catheter used inconjunction with an embodiment of an airlock clearing mechanism andfluid collection & analysis system. Both urine drainage and pressurereadings benefit from the elimination or reduction of airlocks in theurine drainage line.

Sensing Foley catheter 1000 is similar to the sensing Foley cathetershown in FIG. 1. The sensing Foley catheter is shown in use in bladder1014. Note that several of the ports at the proximal end of the cathetershown in FIG. 1 are combined in the embodiment shown in FIG. 10A. Urinedrainage tube 1001 is also shown here. The urine drainage tube may becombined with the sensing Foley catheter or may be a separate component.Urine drainage tube 1001 and/or sensing Foley catheter may also includevent barb 1016, or the vent barb may be a separate component. Airlockclearing mechanism and fluid collection & analysis system 1002 is alsoshown here, and is in fluid communication with urine drainage tube 1001which is in fluid communication with sensing Foley catheter 1000.Airlock clearing mechanism and fluid collection & analysis systemincludes base/controller 1018, fluid collection bag 1020 and reservoiror cassette 1022. The combination of the sensing Foley catheter 1000,the urine drainage tube 1001, and the airlock clearing mechanism andfluid collection & analysis system 1002 are also referred to herein asthe sensing Foley catheter system. The sensing Foley catheter, urinedrainage line, and reservoir/cassette may be disposable and may be soldas a unit. This disposable assembly is shown in FIG. 10C, which includessensing Foley catheter 1000, urine drainage tube 1001 (including ventbarb) and reservoir/cassette 1022.

Vent barb 1016 may include vent, or vents, 1006 as well as urinesampling port 1004. In this embodiment, vent 1006 is preferably madefrom a membrane that permits the transmission of gases, but not liquids,such as hydrophobic membranes. An example of one such exemplary vent isa PTFE (Polytetrafluoroethylene), ePTFE (Expanded PTFE), or Versapor®(from Pall Corporation of Port Washington, N.Y.), membrane, althoughother materials may be used. The vent allows air to enter the systemwhen negative pressure is applied to the drainage tube, and may allowair to exit the system when positive pressure is created due to airlocksin the drainage line. Such a mechanism prevents suction trauma, forexample at the bladder wall. Vents 1006 may incorporate a one-way valvewhich prevents air from exiting the drainage line, or entering thedrainage line. In a preferred embodiment, a one-way valve is used toprevent air from exiting the drainage line, but allows air to enter thedrainage line, via vents 1006. In this manner, the valves also preventurine from coming into contact with vents 1006.

Urine drainage tube 1001 may include several lumens, including pressurelumen 1010, temperature lumen 1008, and urine lumen 1012. Pressure lumen1010 is in fluid communication with pressure sensing balloon 108 as wellas pressure transducer interface 1026 in controller 1018. Temperaturelumen 1008 communicates with the temperature sensor (not shown) in thesensing Foley catheter and also temperature connecter 1024 in thecontroller. Urine lumen 1012 is in fluid communication with opening oropenings 106 and urine reservoir or cassette 1022.

Disposable measurement vessel, collection vessel, chamber or cassettecomponent 1022 is designed to fit into cassette mount, base orcontroller 1018 and to interface with the components of the controller.Controller pump interface (behind cassette pump interface 1148) connectsto pump 1134 and to cassette pump interface 1148 on the disposablecassette component. The pump is designed to create a vacuum inside thecassette component, which is then transferred to the urine drainagelumen in the drainage line. Preferably, the collection vessel/cassetteis rigid in order to maintain a constant volume when the pump appliesnegative pressure. The level of negative pressure applied may bemonitored by a pressure sensor. During clearance of an airlock, thepressure follows a signature curve as shown in FIG. 59. The pressuredecreases as suction is applied, eventually reaching an inflection pointwhen the meniscus of the urine passes the lowest point in the drainagetubing. At this point, less suction is required to continue clearing theairlock, so the pump power can be reduced in order to minimize theamount of suction transmitted to the bladder once the airlock iscompletely cleared. A larger vessel without this pressure-sensingfeature for example, would transmit substantial negative pressure to thebladder once the airlock is cleared and the before the vessel has timeto equilibrate with atmosphere. Controller pressure interface (behindcassette pressure interface 1150) connects to a pressure measurementdevice, such as a pressure transducer, and to cassette pressureinterface 1150. The pressure measurement device is designed to measurevolume of the urine, or other fluid, based on the pressure exerted onthe pressure measurement device, which may be a pressure transducer.Ultrasound transducer interface 1130 is also to provide urine volumemeasurements. The ultrasonic measurements can be used in conjunctionwith the pressure measurements, or either can be used to determineurine, or other fluid, volume output. Active pinch valve 1132 isdesigned to connect to the outflow tubing of the cassette. The pinchvalve is to control the emptying of the cassette vessel and the pinchvalve is controlled by the controller so that it releases urine/fluidwhen the urine output reaches a certain volume in the cassette, asdetermined by the pressure and/or ultrasonic measurements. The volume ofurine in the cassette is measured, and when the urine gets to a certainvolume, the urine is emptied via the pinch valve into urine drainage bag1020. For example, the cassette may be emptied when the volume of urinein the cassette reaches about 50 ml. Alternatively, the cassette may beemptied when the volume of urine in the cassette reaches about 40 ml.Alternatively, the cassette may be emptied when the volume of urine inthe cassette reaches about 30 ml. Alternatively, the cassette may beemptied when the volume of urine in the cassette reaches about 20 ml.Alternatively, the cassette may be emptied when the volume of urine inthe cassette reaches about 10 ml. In this way the urine output volumecan be accurately measured over time.

Alternatively, the controller may utilize a set time between cassetteemptyings and measure the volume of urine in the cassette just prior toemptying. Alternatively, the controller may empty the cassette upon anevent, such as air-lock removal triggered by pump activation. Forexample, the controller may set up a periodic air-lock clearance cycle,followed by measuring of the volume of urine in the cassette, followedby emptying of the cassette.

For example, the controller may control the pinch valve to empty thereservoir/cassette when the urine volume reaches about 50 ml.Alternatively the controller may control the pinch valve to empty thereservoir/cassette every hour after measuring the urine volume withinthe cassette. Alternatively the controller may control the pinch valveto empty the reservoir/cassette during, or after, a urine drainageevent, such as a running of the pump. Or the controller may control thepinch valve to empty the reservoir/cassette using a combination of thesetriggers.

Other technologies may be used to measure urine volume in addition to,or instead of, pressure and/or ultrasound, including pressure-based,resistance-based, capacitance-based, ultrasonically-based, oroptically-based technologies. More than one technology may be used sothat the measurements can be compared to each other to improve theaccuracy of the volume measurements. More than one volume measurementmade by one or more technologies may be used for redundancy, or backup,or in conjunction with each other to obtain more accurate urine volumemeasurements.

Bed hooks 1116 are for hooking the controller to the bed, or otherdevice, as needed. They can also be used to hook the controller to aportable device for patient transport. Collection bag hooks/holes 1102are to mount a drainage bag where the urine/fluid is ultimatelycollected, after the urine/fluid passes through the pinch valve.Collection bag hooks 1102 may be designed to provide strain measurementssuch that the weight of fluid in the bag can be determined and thereforeprovide another method for determining the volume of fluid in the bag.For example, piezoelectric transducers may be used. Specific gravitydeterminations may also be used by the controller to determine usefulvolume measurements based on weight and specific gravity.

Screen 1110 is for displaying information including current urine/fluidvolume status, system status, etc. Screen 1110 may also be a touchscreen and receive inputs, including settings, screen display changes,menu changes, etc. Pressure port 1026 connects to the bladder pressureline 1010, which measures bladder pressures using a sensing Foleycatheter, if used. Alternatively, pressure port may be located withinthe cassette mount underneath cassette 1022 or elsewhere in thecontroller/base. Temperature in port 1024 connects to athermistor/temperature sensor which measures body temperature, eithervia a sensing Foley catheter via lumen 1008, or by other means.Temperature out port 1122 is for transmitting any temperaturemeasurements to an external device and/or monitor. Adapter port 1124 isfor adapting the controller to other devices, such as in the case of aRFID adapter. This could be used to activate any additional/advancedfeatures, such as measurements of IAP, respiratory rate, heart rate,cardiac output, or any other parameters that may be measured by thesensing Foley catheter. This allows the additional parameters to beactivated and paid for by the hospital only when that information isdesired. The activation of advanced features may also be controlled byuse of different disposable components for example. Alternatively,advanced features may be activated by software upgrades which arepurchased, either as part of the disposable, or separately. Softwareupgrades may be delivered wirelessly, by USB dongle, by micro-SD card,by EPROM card, or by other suitable technology. Data for each patientand/or aggregated patients may also be saved by the controller. Thepatient data may be saved to memory, USB, micro-SD card, EPROM card,hard drive, or otherwise. The patient data may be transferred wirelesslyor by wired connection to another storage device, such as a server onthe internet or an intranet. Patient data may be anonymized Patientdata, such as the patient ID, may be stored in an RFID adapter so thatdata specific to a particular patient is recognized by the controllerand associated with the disposable component used by that patient.

Power LED/indicator 1114 is an indication that the power is on or off.Error LED/indicator 1112 is an indicator if any error has occurredwithin the system. Error details can be displayed on screen 1110, butindicator 1112 alerts users that an error exists. Indicators may alsoincorporate sounds or other alerts.

Port 1108 is for downloads, uploads, software upgrades, connecting toother devices etc., such as integration with an EMR (Electronic MedicalRecord) system. Port 1108 may be a USB port or other appropriate port.SD port 1106 is for data downloads. Power port 1104 is for connectingthe controller to the wall or other power source to power thecontroller.

Urine/fluid drainage bag 1020 includes one way valves 1136 connected tooverflow tubing 1138 and outflow tubing 1140 to prevent urine/fluid fromexiting the drainage bag once collected. These valves also prevent airfrom entering the collection vessel 1022 when pump 1134 is pullingvacuum so that the vacuum acts on the drainage tubing and not the bag.In a preferred embodiment, a single valve is used for both the overflowand outflow tubings. Mounting hooks/holes 1102 allow drainage bag 1020to be removably attached to controller 1018. Vent 1142, which may be ahydrophobic or other vent, allows air or gas to exit the drainage bag,but does not allow fluid to exit the bag. This prevents excessive air,and potentially pressure, buildup in the bag, and thus allows forefficient filling of the drainage bag. Graduated markings 1144 show asomewhat crude measurement of the fluid volume in the bag as it iscollected. Outflow valve 1146 may be used to empty the bag offluid/urine. Preferably, the valve is operable easily by one person.Collection bag hooks 1102 when designed as strain measurement elementsmay also force an alarm to sound if the bag is reaching full capacityand needs to be emptied. An alarm may also sound if there isunnecessarily excessive force on the bag, for example if the bag isbeing pulled or is caught on an obstacle as a patient is being moved.

The drainage bag may be made out of clear vinyl or other suitablematerial. The one-way valves may be made out of vinyl or other suitablematerial. The hydrophobic vent may be made out of ePTFE, Versapor, orother suitable material. The outflow valve may be made out of PVC, PC,or other suitable material.

Pressure readings from the sensing Foley catheter may be used to triggerthe pump and therefore the emptying of the drainage tubing. For example,when pressure sensed in the bladder exceeds a preset number, the pumpmay engage to move urine more quickly through the drainage tubing.

The controller/base and/or the reservoir/cassette may include anaccelerometer, or other sensor, to determine when thecontroller/cassette is level and when it is not. An alarm may sound whenthe controller/cassette is not level. Alternatively, urine volumemeasurements may be adjusted to account for the different angle in thesystem.

The bottom of the urine reservoir in the cassette may have roundededges, or be configured in such a way that urine is completely emptiedfrom the cassette when the pinch valve is opened.

FIG. 10B is a detail view of airlock clearing mechanism and fluidcollection & analysis system 1002. Screen 1110 displays the userinterface including patient parameters as well as touch screen, orother, control functions. Heart rate area 1152 shows the patient's heartrate which is determined by the controller based on intra-bladderpressure measurements sensed by the sensing Foley catheter. Respiratoryrate area 1154 shows the patient's respiratory rate which is determinedby the controller based on intra-bladder pressure measurements sensed bythe sensing Foley catheter. Core body temperature area 1156 shows thepatient's core body temperature as sensed by the temperature sensor inthe sensing Foley catheter or otherwise. Urine output area 1158 showsthe patient's current and/or average urine output which is determined bythe controller based on urine volume measurements as measured bypressure measurement device connected to pressure interface 1150 and/orultrasound transducer interface 1130. Sepsis Index area 1160 shows thepatient's likelihood of sepsis which is determined by the controllerbased on one or more patient parameters collected and/or calculated. Forexample, temperature, heart rate abnormalities, respiratory rateabnormalities and/or urine output or other factors may be considered indetermining sepsis risk. Trending in these parameters may also be usedin assessing risk. For example, reduced urine output, increased heartrate, increased or decreased core temperature may be indicators ofsepsis.

Other risk assessments may be determined by the controller and displayedin addition to, or as an alternative to, the Sepsis Index. These includerisk assessments of acute kidney injury, urinary tract infection,intra-abdominal hypertension, abdominal compartment syndrome, infectionrisk, sepsis, ARDS (Acute respiratory distress syndrome) and others. Forexample, a sample risk algorithm of acute kidney injury and urinarytract infection is shown in FIG. 58A. A sample risk algorithm for acutekidney injury, sepsis and acute respiratory distress syndrome is shownin FIG. 58B. Measured urine parameters may include conductance, specificgravity, urine output, presence of infection, bacteria, white bloodcells, oxygen tension and others.

Graphical indicator 1162 shows historical data of any of these areas.For example, a user may be able to toggle the graphical display bytouching the screen and show the patient's history of urine output,temperature, heart rate, respiratory rate, Sepsis Index, risk of acutekidney injury, urinary tract infection, intra-abdominal hypertension,abdominal compartment syndrome, infection risk and others, or any otherpertinent parameter. The time frame for the history may be all time,daily, hourly, or any period set by the user. Any risk factor that isout of range, so at an elevated risk, may be shown automatically here orelsewhere on the display. Alerts and/or ranges may be set by the user,and may include absolute values, as well as trends over time. Forexample, an increase in core body temperature of more than 2 degreesover a specific time frame may display a visual or sound an audiblealert.

FIG. 11 shows an embodiment of the sensing Foley catheter system(including airlock clearing mechanism, fluid drainage, collection &analysis system/controller) similar to that shown in FIG. 10A where vent1180 is located on controller 1018 or reservoir/cassette 1022, insteadof on vent barb 1182. In this embodiment, vent 1180 is in fluidcommunication with urine drainage lumen 1012 via vent lumen 1184 whichfluidly connects to urine lumen 1012 at barb 1182. In this embodimentthe barb design is simplified and the drainage tubing simply has anadditional lumen compared to the embodiment shown in FIG. 10A. The ventmay be located anywhere in the system and the fluid interface with theurine lumen may be anywhere in the system as well.

FIG. 12 shows an embodiment of the sensing Foley catheter system similarto that shown in FIG. 10A where, as opposed to the system shown in FIG.10A, no pressure balloon is utilized. Instead, pressure is measuredinside the bladder via the urine lumen (or other lumen) in the sensingFoley catheter. In this embodiment, the pressure lumen 1202 is connectedto the vent 1204, or elsewhere in the system outside the patient, andis, at lease periodically, in fluid communication with thedrainage/urine lumen of the catheter. In this embodiment, the sensingFoley catheter system may be used with any standard Foley catheter. Notethat any embodiments of the sensing Foley catheter system may be usedwith a standard Foley catheter. The system shown in FIG. 12 may also beused without pressure lumen 1202, and with a standard Foley catheter, ifpressure measurements in the bladder are not desired.

FIG. 13 shows an embodiment of the sensing Foley catheter system similarto that shown in FIG. 12. In this embodiment, valve 1302 may be utilizedto periodically close pressure lumen 1202 to the urine drainage lumen.The valve can be opened, by the controller or manually, when a pressuremeasurement is taken, and closed, again by the controller or manually,when a bladder pressure reading is not needed.

FIGS. 10A, 10B, 11 and 12 show embodiments of the sensing Foley cathetersystem which include a vent near the patient end of the drainage tubethat allows air to enter the drainage tube if negative pressure iscreated either due to a siphon in the drainage tube or due to thepumping mechanism or both. Without a vent/filter, such negative pressurecan lead to suction trauma, such as trauma caused to the mucosal liningof the bladder. Note that these embodiments are different than deviceswhere the vent(s) allow air to escape, but not enter, the drainage tube.

Urine drainage lumens preferably have an inner diameter less than about0.25 inches such that liquid in the lumen maintains circumferentialcontact with the lumen, which forms a seal and allows the liquid toadvance when a pumping mechanism is activated. There may be multipledrainage lumens to prevent blockage of flow if the pumping mechanismfails. In these embodiments, the drainage lumens are preferentiallygenerally empty, which may require continuous activation of the pumpingmechanism. Alternatively, the pumping mechanism may be activated priorto making a measurement of volume to ensure that all the liquid has beendrained, which reduces the power requirements of the device.

Some embodiments of the sensing Foley catheter system include detectinga pressure spike in the drainage line while a pressure within the bodilyorgan remains constant; and using a pump to create negative pressurethrough the drainage line until the pressure in the drainage line equalsthe pressure in the bodily organ.

In one embodiment, the vent has a resistance to airflow that is greaterthan the resistance to liquid flow from the patient, such that anybuildup of liquid in the patient is purged into the drainage line beforeair enters through the vent. For example, in the case of urine drainage,a full bladder will be emptied into the drainage line before air entersthrough the vent as long as the resistance of airflow through the ventis greater than the resistance of urine flowing through the patient'scatheter. However, the vent preferably has the smallest possibleresistance to airflow while meeting this requirement in order tominimize suction trauma.

In another embodiment, the vent has very little resistance to airflow sothat the bladder is further protected from suction, and the controllerpump is activated to clear airlocks at more frequent intervals, forexample every 1 minute, every 5 minutes, or every 10 minutes, to keepthe drainage line clear of urine. When the pump is activated, it maycontinue to run until it detects that no more urine is draining,indicating that the bladder has completely emptied. Alternatively, thepump may run for a set period of time, for example about 30 seconds,about 1 minute, about 3 minutes, about 5 minutes or about 10 minutes.

The pumping mechanism used can be any suitable mechanism, including, butnot limited to peristaltic pumps, diaphragm pumps, vane pumps, impellerpumps, centrifugal pumps or any other suitable pump. The pump may bepowered by a wall outlet, battery, human power, or any other suitablesource. In some embodiments, the vacuum is in the range of about 0 to−50 mmHg. The negative pressure may alternatively be supplied by wallvacuum, often present in hospital rooms. Pumping mechanisms may includea peristaltic-like pump or suction applied directly to the collectionvessel. The pump may be located on the patient side of the drainagereservoir, or the pump preferably may be located on the non-patient sideof the drainage reservoir/cassette, so that the reservoir is between thepatient and the pump. In order to function properly, the pump shouldpreferably be capable of generating negative pressures equal to themaximum liquid column height in the drainage tube. This may be half thelength of the drainage tube. With urine drainage tubes having a maximumlength of 60 in, the maximum negative pressure required would be around30 in H2O, or 56 mmHg.

Other technologies may be used to urge urine through the tubing and/orsystem including pulsatile mechanical, vibratory acoustic, thermal,vibratory, pinching, rolling or electromagnetic stimulus to cause atleast one of a movement of the drainage line and the bodily fluidswithin. In some embodiments, the rolling stimulus comprises compressingmultiple lumens sequentially such that the lumens are never allcompressed at the same time.

In another embodiment, air locks are removed by means of a collapsibledrainage tube that resides in a more stiff kink-resistant tube. FIG. 14Ashows such an embodiment in its un-collapsed form. Inner collapsibledrainage tube 1402 is inside outer kink-resistant tube 1404. FIG. 14Bshows the embodiment with the inner collapsible tube collapsed.Periodically, the drainage tube is collapsed, such as by applying apositive pressure to the space between the collapsible tube and thekink-proof tube or by applying negative pressure to the inside of thecollapsible tube. Collapsing of the drainage tube then urges urine awayfrom the patient and toward the collection vessel.

In another embodiment, the drainage lumen clearing mechanism comprises atube with an inner diameter less than about 0.25 inches, such that noair pockets are able to move up the length of the tube. This is possibledue to the surface tension within the smaller tubes, which preventmovement of fluid when one end of the tube is closed to atmosphere (asin the case of the bladder). Thus, the drainage tube always remains fullof urine, and for each volume of urine produced the same volume of urinemust exit the drainage tube, as urine is incompressible. In anotherembodiment, the inner diameter is less than 0.125 inches. In anotheraspect, said drainage tube acts as a siphon and provides a small, safeamount of vacuum to the bladder. Alternatively, with a small lumendrainage tube, air is allowed to periodically enter the tube lumen viathe vent/valve. The negative pressure caused by the pump may encouragethis. Urine is encouraged to continue flowing into the collectionreservoir due to the negative pressure caused by the pump, thuspreventing airlocks.

The use of small-diameter tubing also results in a smaller volume ofresidual urine in the drainage tube compared with the prior art. Havinga smaller residual volume is preferential, as it allows urine to movemore quickly from the patient's bladder to the collection vessel. Thespeed of this transport is important in order to take measurements ofthe urine that has been produced more recently. This is particularlyimportant for patients with low rates of urine production, as it takestheir urine even longer to be transported from the bladder to thecollection vessel. For example, for a patient producing only 10 mL/hr ofurine with a standard drainage tube (around 40 mL residual volume),measurements of their urine in the collection vessel will lag true urineproduction by 4 hours. By contrast, with smaller tubing (such as tubinghaving around 5 mL residual volume), measurements will only lag trueproduction by 30 minutes. In some embodiments utilizing a small diameterlumen, with or without a vent/valve, a pump, to supply negative pressureto the drainage line, is not required.

FIG. 15 shows an embodiment of the device that is well-suited fordraining chest tubes or other drainage tubes that apply constantnegative pressure to the patient. Although these embodiments may also besuitable for draining urine from the bladder or fluid from othercavities. Any of the features disclosed in relation to chest tubedrainage may also be applied to bladder drainage or other body cavitydrainage. Liquid is drained from the patient through drainage lumens1585, which connect to collection vessel 1582. Drainage is assisted bypulling negative pressure on the collection vessel 1582, for example byattaching a suction tube 1583 to the hospital wall suction. Suction mayalso be applied with other methods, such as with a pump as disclosedelsewhere herein. Air enters the drainage lumens 1585 through a valve1584, which has a crack pressure equal to the desired negative pressure.By choosing the correct crack pressure (for example, −15 to 0 mmHg, or−10 mmHg), the pressure applied to the patient will remain at thispressure as long as the hospital wall suction/pump can generatesufficient suction at the collection vessel 1582. Preferably, thedrainage lumen(s) used for draining chest tubes are as large as possiblewhile maintaining a siphon. Suitable inner diameters include, but arenot limited to, about ¼″, about 5/16″, or about ⅜″.

FIG. 16 shows another embodiment of the device that is well-suited fordraining chest tubes or other drainage tubes that apply constantnegative pressure to the patient. Liquid is drained from the patientthrough drainage lumens 1688, and negative pressure is applied using apumping mechanism 1686. A pressure sensor 1687 resides within drainagetube at the patient end, and thereby measures the pressure applied tothe patient. The measurement value obtained by the sensor 1687 is sentback to the controller controlling the pumping mechanism 1686, and thepressure generated by the pumping mechanism 1686 is adjusted in order tokeep the pressure at the sensor 1687 (and patient) at the desired level.Pressure sensor 1687 may also be located elsewhere in the system. Thesensor may also be used for passive monitoring of pressure at thepatient end of the tube to provide clinicians with information about thelevel of suction being applied. Although FIG. 16 shows the pump on thepatient side of the drainage reservoir, the pump may alternatively be onthe other side of the drainage reservoir, so that the reservoir isbetween the patient and the pump.

In another embodiment of the invention used for draining chest tubes,the volume of the fluid drained is measured in order to provideinformation to clinicians about the drainage status of the chest tube.This measurement can be accomplished by any suitable means, particularlythose described within for measuring urine volume.

In addition to eliminating air locks, several of the air lock clearancedesigns detailed above have been found to effectively clear deposits andblood clots from urine drainage lines. These problems plague currenturine drainage tubes, particularly those with smaller lumen drain tubesand monitoring technologies at the drainage bag, and this inventionprovides an advance in the state of the art by automating the clearingof these drainage blocking debris and clots. This feature isparticularly useful when used in conjunction with pressure sensingeither in a balloon at the tip of the Foley or in fluid communicationwith the bladder. This allows for the monitoring of pressure and vacuumin the bladder and allows for more aggressive pumping based on actualbladder pressure until the clot/obstruction is cleared. Without thispressure/vacuum sensing, the pumping of fluid in the drain tube maygenerate clinical sequelae in the bladder, such as suction trauma, dueto the exposure of the bladder mucosa to excessive vacuum.

In another embodiment, shown in FIG. 17, a gas-sampling lumen 1790 runsthe length of the drainage tube and terminates with a gas-permeable butliquid-impermeable filter 1791 that remains in contact with urine, themeniscus 1792 of which is further from the patient than the filter. Whena measurement of oxygen, carbon dioxide, or any other gas is needed, theair within gas-sampling lumen 1790 is pulled into base 1789 of thedrainage device for analysis. This configuration allows for accurate gasanalysis even with embodiments of the device that allow air into thedrainage line such as those illustrated in FIGS. 10 through 16.

As shown in FIG. 18, an active vented system comprises air vent 1802,drainage line 1804, collection vessel 1806, and pump 1808. The ventedside of the drainage line is connected to the patient. In oneembodiment, the fluid drained is urine, and the connection is made to aurinary catheter. Fluid flows from the patient through the drainage lineand collects in the collection vessel. The pump in this embodiment isnot acting directly on the drainage line, but is pulling a vacuum on thecollection vessel. The pump facilitates drainage by pulling negativepressure on the collection vessel, which urges fluid through thedrainage line. Preferably, the collection vessel is rigid in order tomaintain a constant volume when the pump applies negative pressure. Thevent on the patient side of the drainage tube is preferably a vent thatallows the transmission of gas (preferably air), but prevents thetransmission of liquid. The vent thereby prevents substantial negativepressure from being applied to the patient by allowing atmospheric airto enter the system. Such a mechanism prevents suction trauma, forexample at the bladder wall.

The pump in this system can be any suitable pump for pumping gases,including, but not limited to peristaltic pumps, diaphragm pumps, orcentrifugal pumps. In order to function properly, the pump shouldpreferably be capable of generating negative pressures equal to themaximum liquid column height in the drainage tube. This may be half thelength of the drainage tube. With urine drainage tubes having a maximumlength of 60 in, the maximum negative pressure required would be around30 in H2O, or 56 mmHg.

As shown in FIG. 19, an active vented system for draining bodily fluidsmay have additional vents. One such vent, vent 1962, may be located onthe collection vessel and allows air to escape the collection vessel.This prevents the buildup of pressure as new fluid enters the vessel, byallowing each volume of fluid entering the system to be offset by thesame volume of air exiting the system. Another such vent, vent 1964, maybe located between the collection vessel and the pump. This vent allowsthe transmission of gas (preferably air), but prevents the transmissionof liquid, in order to prevent bacteria or viruses from entering orexiting the collection vessel and drainage tube. Preferably, this ventis sterility-grade, meaning air that passes through is considered to besterile. A vent (not shown here) may or may not be present at thepatient end of the drainage line.

As shown in FIG. 20, pressure offsetting may be accomplished with asingle vent on the collection vessel. In this case, the vent, vent 2072,may be between the collection vessel and pump as before, but anadditional valve 2074 allows air to escape the collection vessel in thepresence of positive pressure. This valve is preferably a one-way valvethat allows air to exit, but not enter, the system. When the pumpactivates, the one-way valve closes, and air must be pulled from thecollection vessel, thereby generating negative pressure in thecollection and facilitating flow of fluid through the drainage line. Avent may or may not be present at the patient end of the drainage line(not shown here).

Detecting Infection

FIG. 21 shows an embodiment of a collection vessel, chamber or cassettewhich may be included in the sensing Foley catheter system to detectbacteria, blood and/other substances in the urine using UV/light/Ramanspectroscopy. Cassette 2100 includes container wall 2102, which ispreferably rigid. Urine 2106 is collected in the cassette. If urine iscollected too quickly, or there is some impediment to the cassette'semptying, overflow area 2104 will allow any excess urine to drain fromthe cassette. Cassette 2100 may include an optically clear section 2110which is preferably incorporated into an outside wall of the cassette,and reflector section 2112, which is preferably on, or incorporatedinto, an inner wall of the cassette. “Optically clear” here means ableto transmit light at the needed analysis wavelength(s) through theoptically clear section. Preferably the optically clear section made ofa material which is able to transmit UV light, such aspolymethylmethacrylate, polystyrene, acrylic, quartz, etc. The wallthickness may need to be thin enough to allow the appropriate UVwavelength(s) to be transmitted through the optically clear section. Forexample, the thickness of the optically clear section may be from around0.5 mm to around 0.7 mm thick. Alternatively the thickness of theoptically clear section may be from around 0.5 mm to around 0.6 mmthick. Alternatively the thickness of the optically clear section may befrom around 0.6 mm to around 0.7 mm thick. Alternatively the thicknessof the optically clear section may be less than around 0.7 mm thick.

UV/light transmitter/receiver 2108 transmits UV or other wavelengthlight in the appropriate wavelength through optically clear section2110, through the urine in the cassette, to reflector 2112 in thecassette. The UV/light transmitter/receiver may be incorporated into, orconnected to, the controller component of the sensing Foley cathetersystem. The light is reflected back to the UV/light receiver which thentransmits the collected data to the controller for signal analysis. Morethan one UV/light wavelength may be analyzed either simultaneously orserially. Light outside of the UV range may be used in addition to lightwithin the UV range. The volume of urine physically between thetransmission and receiving of the light is preferably maximized for astronger signal reflecting the concentration of one or more substancesin the urine. The transmitter/receiver may be located as shown in FIG.21, or in other areas of the cassette. The receiver may be in adifferent location than the transmitter and the reflector may or may notbe necessary nor present. Because the urine in the cassette isfrequently emptied, the UV/light absorption measurements can becollected over time and increases and/or decreases in the level of oneor more substances in the urine can be tracked over time, inessentially, or nearly, real time. This is particularly important inidentifying infection quickly, including urinary tract infection andCatheter-associated Urinary Tract Infection (CAUTI). The UV/lightdetection may also be performed elsewhere in the sensing Foley cathetersystem, including in the drainage tubing, a separate sampling area etc.

Infection may be identified by analyzing the urine for bacteria, redblood cells, and plasma and/or white blood cells using UV/lightspectroscopy. FIG. 22 shows the various absorption wavelengths of E.coli, red blood cells, and plasma in urine to light. The presence ofplasma/white blood cells and/or bacteria in urine are both indicators ofinfection. The presence of red blood cells may not be indicative ofinfection. Therefore it is desirable to distinguish between red bloodcells and bacteria/plasma/white blood cells in the urine. Since thespectroscopic signature for red blood cells differs significantly fromthose of either bacteria or plasma/white blood cells, at a wavelength ofabout 414 nm, the signal for red blood cells can be separated from thoseof bacteria and/or plasma/white blood cells, and an infection can beidentified by analyzing the absorption of light at this wavelength.Because the signature for plasma and bacteria differ from each other atthe wavelengths of 260 nm and 280 nm, these wavelengths can be used todistinguish between plasma and bacteria. However, it is likely that bothplasma and bacteria may be present during an infection.

Other wavelengths and other technologies may also be used to detectvarious substances in urine or any collected/drained bodily fluid.UV/light absorption may also be used to detect turbidity. A dye or drugor reactive substance may also be introduced into the system, or becoated on the inside of the system, cassette, etc., to react with asubstance in the urine to aid in analysis. Any type of sensor may beused to sense any substance or quality of the collected urine in eitheran intermittent or continuous basis, real-time basis. For example,sensor(s) to detect Magnesium in the urine may be used to diagnosepreeclampsia or eclampsia. Lactate sensors may be used to test forlactate (or lactate dehydrogenase) in the urine. The identification oflactate in urine may be an early indicator of sepsis. Lactate sensorsmay include enzymatic lactate sensors. For example, lactate sensors asdisclosed in Weber (Weber J., Kumar A., Kumar A., Bhansali S. Novellactate and pH biosensor for skin and sweat analysis based on singlewalled carbon nanotubes. Sens. Actuators, B, Chem. 2006; 117:308-313),and/or Mo (Mo, J W, Smart, W, Lactate biosensors for continuousmonitoring. Front Biosci. 2004 Sep. 1; 9:3384-91), both of which areincorporated herein by reference in their entirety, may be used.

Drug or drug residue may be detected in the collected urine usingappropriate sensors. Other substances or characteristics of thecollected urine which may be sensed include color, clarity, odor,specific gravity, osmolality, pH protein, glucose, creatinine, nitrites,leukocyte esterase (WBC esterase), ketones, red or white blood cells,casts, crystals, bacteria, yeast cells, parasites, Squamous cells, etc.

CAUTI or infection may be identified and/or reduced by several methodsincluding: analyzing the urine using spectroscopy, light wavelengthanalysis etc. to identify contaminates early, reducing trauma caused tothe bladder by suction, reducing urinary retention in the bladder,reducing bacterial or microbial presence by the use of an antimicrobialcoating or embedded material such as silver or other material,increasing the accuracy of pressure measurements within the bladder byreducing suction within the bladder, increasing accuracy of urine outputmeasurement by reducing airlocks in the system and suction within thebladder. Pressure spikes caused by suction in the bladder may be definedas pressure readings below about −20 mmHg. Alternatively, pressurespikes caused by suction in the bladder may be defined as pressurereadings below about −10 mmHg to about −20 mmHg. Alternatively, pressurespikes caused by suction in the bladder may be defined as pressurereadings below about −10 mmHg.

FIG. 23 shows an embodiment of the cassette which includes baffle orflap 2302. This baffle/flap is meant to prevent urine from wicking alongthe inside walls of the cassette as shown by the dotted arrow. Thebaffle will prevent the urine from wicking beyond the point of thebaffle so the urine will fall back into the measurement reservoir below.

Priming

An aspect of the disclosed technology that is particularly advantageousin achieving a high resolution signal from which pressure profiles fromparticular physiologic sources (such as peritoneal pressure, respiratoryrate, and cardiac rate, relative pulmonary tidal volume, cardiac output,relative cardiac output, and absolute cardiac stroke volume) may bemonitored relates to adjusting and maintaining a balance of pressure oneither side of the pressure interface represented by the membrane of thepressure sensing balloon. This balance of pressure may be referred to asa pressure differential. In some embodiments the preferred pressuredifferential is at or around zero. In some embodiments the preferredpressure differential may be a different value. Pressure impinging onthe external face of balloon (facing the internal aspect of the bladder)is subject to change according to the physiology of the patient.Pressure on the internal face of the balloon (which is in fluidcommunication with the fluid column) is subject to degradation becauseof fluid leakage and imperfect seals.

Upon first insertion of the sensing Foley catheter, external pressure istypically applied to the fluid column and against the pressure interfaceto a first approximation of pressure being exerted on the pressureinterface from within the bladder. Pressure signals, as measured acrossa pressure interface, have a maximal amplitude when the pressuredifferential is about zero. Accordingly, the amplitude of a pressuresignal can be used to tune the pressure being applied from the fluidcolumn against the pressure interface. This process of applying anappropriate amount of pressure against the interface may be referred toas priming the fluid column or priming the balloon. Inasmuch aspressures on either side of the pressure interface may change, asdescribed above, the fluid column may need to be re-primed or re-tuned,from time to time. The necessity of re-priming can be monitored bytesting small changes in pressure so as to achieve maximal amplitude ofa pressure signal profile. Alternatively, the priming can automaticallyoccur via the controller on a periodic basis.

Embodiments of the disclosed system and method include automaticpressure tuning by a controller. Accordingly, the tuning system candetect the optimum target pressure and volume to inflate the balloon bymonitoring sensed pressure signals and adding or removing air or fluidvolume as needed. For example, upon insertion of the catheter, apressure tuning circuit that regulates the balloon volume and pressuremay inflate the balloon until it detects a physiologic-sourced pressurerate. Upon sensing that rate, the pressure tuning controller may add orsubtract minute amounts of air in a routinized or programmed sequence ofsteps until the amplitude of the sensed wave is greatest. The controlfeedback loop between the optimally tuned pressure (manifesting asballoon pressure and volume) and the sensed physiologic pressure profileiterates continuously and or as needed to ensure high fidelitymeasurement of the physiologic data. In some embodiments, automaticpressure tuning may be performed in the apparent background while thephysiologic data is being transmitted and displayed; in otherembodiments the system may suspend transmission of physiologic dataduring a pressure tuning sequence.

Embodiments of the disclosed technology include a gas delivery systemthat can deliver gas in a priming operation, whereby pressure can beapplied to a fluid column proximal to the proximal-facing aspect of thepressure interface. A source of gas, such as compressed air or liquid isheld in a storage tank. Using CO₂ as an example, CO₂ is controllablyreleased from the storage tank through a pressure regulator that canstep pressure in the tank (for example, pressure of about 850 psi) downto the range of about 1 psi to about 2 psi. Released gas passes througha filter and a pressure relief valve set at about 2.5 psi. The pressurerelief valve is a safety feature that prevents flow through of gas at alevel greater than 2.5 psi in the event of failure of the upstreamregulator. CO₂ exiting the pressure relief valve next passes through afirst solenoid-controlled fill valve to enter the catheter line,ultimately filling the balloon that comprises the pressure-sensinginterface. Pressure within the balloon is allowed to rise to a level ashigh as 30 mm Hg, whereupon the first solenoid-controlled valve closes.A second solenoid-controlled valve, distal to the first valve operatesas a drain valve, which can release pressure from the catheter to atarget pressure. Alternatively, the drain valve may be activated until arespiratory waveform is detected after which the balloon will beoptimally primed and the valve will be closed. The drain valve may besubject to proportional control, operably based on voltage orpulse-width modulation (PWM), which allows a drain rate sufficientlyslow that the target pressure is reached and the valve can be closedprior to overshoot. Alternatively, a peristaltic or other air pump maybe utilized to fill the balloon with room air.

FIG. 24 shows a graph representing a pressure balloon priming method insome embodiments. Here, small volume bursts (roughly about 0.3 cc) offluid volume are added to the pressure sensing balloon and the pressurewithin the balloon is measured Small volume bursts of fluid areintroduced until the measured pressure within the balloon settles to astable pressure 2401. This transition is shown at inflection point 2402.Volume bursts are introduced past this point until the measured pressurestarts to rapidly increase (for example if slope 2404 of the curve isgreater than about 2 mmHg/10 ms). This inflection point is shown at2406. At this point the pressure within the balloon is reduced to apressure around or slightly above stable pressure 2401. This pressurerepresents the prime pressure measuring pressure in some embodiments.This process is also represented in the flowchart in FIG. 27.

Alternatively, priming of the pressure balloon may involve pressurizingthe pressure balloon well above zero mm Hg, then removing small volumesof air/gas/fluid and monitoring the pressure balloon pressure. Thepressure balloon pressure will stabilize, or plateau, as it approachesoptimal primed pressure. To determine this optimal pressure, pressuremeasurements are taken as small volumes of air are removed from thepressure balloon, when subsequent pressure measurements are essentiallythe same (within about 2 mm Hg of each other), the balloon is at optimalprimed pressure. If 2 subsequent measurements are not essentiallyequivalent, the pressure balloon is re-pressurized well above zero mm Hgand the process is repeated. The pressure measurements taken as smallvolumes of air are removed from the pressure balloon may be taken overabout 5 to about 15 seconds to compensate for the effect of respirationon the pressure measurements. In some embodiments, the pressure signalmay require a short stabilization period after the small volume ofair/gas/fluid is removed from the pressure balloon before the pressuremeasurement is taken.

The small volume bursts of fluid may be from around 0.2 cc to around 0.4cc. The small volume bursts of fluid may be from around 0.1 cc to around0.5 cc. The small volume bursts of fluid may be up to around 0.5 cc. Thesmall volume bursts of fluid may be up to around 1.0 cc.

FIG. 25 shows a graph representing a pressure balloon priming method insome embodiments. This method is similar to that shown in FIG. 24,except that the pressure is increased within the pressure sensingballoon more smoothly, without the bursts shown in FIG. 24. Fluid volumeis added to the pressure sensing balloon and the pressure within theballoon is measured. Balloon pressure is increased until the measuredpressure within the balloon settles to stable pressure 2505. Thistransition is shown at inflection point 2506. Balloon pressure isincreased past this point until the measured pressure starts to rapidlyincrease (for example if slope 2510 of the curve is greater than about 2mmHg/10 ms). This inflection point is shown at 2508. At this point thepressure within the balloon is reduced to a pressure around or slightlyabove stable pressure 2505. This pressure represents the optimal, orprime, pressure in some embodiments. This process is also represented inthe flowchart in FIG. 28.

FIG. 26 shows a flowchart of the balloon priming process of certainembodiments of the invention. Embodiments of the disclosed system andmethod include automatic pressure tuning by a controller. Accordingly,the tuning system can detect the optimum target pressure and volume toinflate the balloon by monitoring sensed pressure signals and adding orremoving air volume as needed. For example, upon insertion of thecatheter, a pressure tuning circuit that regulates the balloon volumeand pressure will inflate the balloon until it detects aphysiologic-sourced pressure rate. Upon sensing that rate, the pressuretuning controller will add or subtract minute amounts of air or fluid(roughly about 0.3 cc) in a routinized sequence until the amplitude ofthe sensed wave is greatest. The control feedback loop between theoptimally tuned pressure (manifesting as balloon pressure and volume)and the sensed physiologic pressure profile iterates continuously and oras needed to ensure high fidelity measurement of the physiologic data.In some embodiments, automatic pressure tuning may be performed in theapparent background while the physiologic data is being transmitted anddisplayed; in other embodiments the system may suspend transmission ofphysiologic data during a pressure tuning sequence.

The minute amounts of air or fluid may be from around 0.2 cc to around0.4 cc. The minute amounts of air or fluid may be from around 0.1 cc toaround 0.5 cc. The minute amounts of air or fluid may be up to around0.5 cc. The minute amounts of air or fluid may be up to around 1.0 cc.

Loop Controller

Certain patient parameters measured by the sensing Foley cathetersystem, and by other means, are impacted by, and/or impact, a patient'streatment through medical treatment devices.

The loop controller can be integrated with the controller of the sensingFoley catheter system (either in the same device or in separate devices)to interpret the patient parameters to control medical treatment of thepatient.

For example, IAP may be used to control IV infusion rate. If IAP becomestoo high, infusion rate may be reduced or stopped until the IAP returnsto an acceptable range. IAP in combination with relative stroke volumeand/or stroke volume variability (variability in the size of the cardiacpulses seen in the bladder, etc. during the respiratory cycle) may allowfor superior control of IV fluid or blood product infusion using IAP asindicator of excess fluid and relative stroke volume increase andreduction in stroke volume variability as indicators that additionalfluid is required. Urine output may be further added to the control loopproviding an indicator that fluid status has been restored with returnof urine output. Heart rate in combination with respiratory rate may beused to control drug infusion (drug type, infusion rate, frequency,dosage etc.). In this way, drugs may be used to bring the patient to amore stable condition which is determined by the heart and respiratoryrate. IAP and respiratory rate may also be used to control a mechanicalventilator or respirator. As IAP rises, the positive end-expiratorypressure (PEEP) delivered by the mechanical ventilator should also riseto overcome this pressure. An indicator that the ventilation is notadequate can be seen in the tissue oxygenation and/or the naturalrespiratory rate which may be seen as a signal underlying the mechanicalventilation. This signal may either be extracted during mechanicalventilation or, preferably, the loop controller may pause the mechanicalventilator to allow more precise and accurate detection of theunderlying respiratory rate/respiratory drive. This IAP, tissueoxygenation and/or respiratory rate may be used to alert the provider toa worsening of the patient's condition and/or may be used to provideautomated adjustment of ventilator settings including respiratory rate,PEEP, % O2 inspired and other settings. In the ideal scenario theseparameters may be used by the loop controller to monitor and controltherapies in a manner that is informed by machine learning andalgorithmic tuning. These are just a few examples, but many combinationsexist. One or more parameters can be used to control one or moretreatment devices.

FIG. 29 shows an embodiment of a loop controller in a patientenvironment. In this example, the loop controller is receiving patientparameter input from sensing Foley catheter 2902. The sensing Foleycatheter resides in patient bladder 2904 and includes retention balloon2908 and pressure sensing balloon 2910. The sensing Foley catheter mayinclude other sensors as disclosed herein.

Sensing Foley catheter 2902 includes a retention balloon inflationlumen, a pressure balloon sensing lumen, and a urine lumen. Pressuresensing balloon 2910 is connected to the pressure sensing lumen which isconnected to pressure transducer 2920 which may be incorporated intocontroller 2928. The urine lumen is connected to urine output tube 2912.The urine output tube empties into urine reservoir 2914 which may beconnected to urine volume measurement device 2916 or may be incorporatedinto the controller as disclosed herein. In addition, urine output maybe controlled by urine pump 2918, which may be located on the urinedrainage tubing, or may be incorporated into the controller, or may belocated on the non-patient side of the controller as disclosed elsewhereherein.

This patient is shown with respirator mask 2922, which is fed byrespirator tube 2924. The flow and makeup of the respiration gas iscontrolled by respirator 2926.

Loop controller 2928 is connected to urine volume measurement device2916, urine pump 2918, pressure transducer 2920, and respirator 2926 viaconnectors 2930, 2932, 2934, and 2936 respectively. The connectors maybe wired or wireless. Alternatively, in this and other embodiments, someor all of urine volume measurement device 2916, urine pump 2918, and/orpressure transducer 2920 may be incorporated into controller 2928.

In this example, loop controller 2928 receives patient parameter inputsfrom urine volume measurement device 2916 and pressure transducer 2920and using the information provided by these parameters, can controlurine pump 2918 and respirator 2926. Some parameters which the loopcontroller may receive from the sensing Foley catheter include IAP,respiratory rate, heart rate, stroke volume, tissue oxygenation, tissueperfusion pressure, temperature, urine analytes, urine output rate, andother parameters, including those disclosed herein.

For example, if the loop controller receives parameter informationindicating that the patient's IAP is elevated, the loop controller maycontrol the respirator perfusion rate, pressure or other parameters. Theloop controller may incorporate data from one or more input parametersand control one or more treating medical devices. For example, based onelevated IAP and abnormal tissue oxygenation parameters received, theloop controller may control the output of respirator 2926 and also theurine output rate by controlling urine pump 2918.

The loop controller continues to monitor the patient parameter(s) andadjust the treating medical device(s) accordingly. As the patientparameters normalize, the control of the treating medical devices isadjusted accordingly so that the feedback loop controlled by the loopcontroller may be a closed loop. The loop may also be adjusted manuallywhen necessary in which case the loop may be an open loop or semi-closedloop.

FIG. 30 shows another example of the loop controller in a patientenvironment. In this example, the patient has intravenous (IV) line 3002in a blood vessel in an arm. IV fluid bag 3004 is elevated to allow theIV fluid to drip and/or flow into the patient via IV line 3002. Valve3006 controls the flow rate of the IV fluid into the patient by allowingthe fluid to flow freely, restricting the flow, or stopping the flow.Here valve 3006 is controlled by loop controller 2928 via connection3008. IV fluid bag 3004 may contain hydrating fluid and/or medications.One or more than one IV bag may be involved and one or more than onevalve may control the IV bag(s). The loop controller may control theflow and content of IV fluid(s) to the patient based on patientparameters received by the loop controller.

FIG. 31 shows another example of the loop controller in a patientenvironment. In this example, the patient has fluid drainage line 3102inserted into the abdomen. Fluid from the abdomen may flow from thepatient to receptacle 3104. The flow of fluid may be controlled by pump3106 which is controlled by loop controller 2928 via connection 3108.The loop controller may control the flow of fluid from the patient toreceptacle 3104 via pump 3106 based on patient parameters received. Forexample, if IAP is abnormally high, loop controller may increase therate of, or initiate, fluid removal from the patient by controlling pump3106.

FIG. 32 shows another example of the loop controller in a patientenvironment. In this example, the patient has intravenous (IV) line 3202in a blood vessel in an arm. Drug infusion device 3204 controls the flowrate of a drug into the patient via IV line 3202. More than one druginfusion device may be used. Here drug infusion device 3204 iscontrolled by loop controller 2928 via connection 3206. Drug infusiondevice 3204 may contain any appropriate fluid and/or medications. Theloop controller may control the flow and content of a drug or drugs tothe patient based on patient parameters received by the loop controller.

These examples show some of the medical treatment devices which can becontrolled by the loop controller, but any medical treatment device canbe used.

FIG. 33 is a detailed diagram of the loop controller. Loop controller2928 can receive one or more patient parameter inputs from a sensingFoley catheter or other device. These inputs include, but are notlimited to, urine output volume and rate, pressure profile from thebladder, and sensor info from a sensing Foley catheter or other device.Pressure profile info from the bladder can be further analyzed todetermine IAP, respiratory rate, heart rate, stroke volume, sepsisindex, AKI index and other patient parameters. This analysis may beperformed in loop controller 2928 or in a separate controller which isconnected to loop controller either by a wired or wireless connection.The connection may be via an internet, intranet, WAN, LAN or othernetwork, or it may be local via Bluetooth, Wi-Fi, etc.

The loop controller receives the input or inputs and analyzes the datato determine whether a medical treatment device controls needs to bechanged. One or more medical treatment devices may be controlled tobring patient parameters into target ranges. Once patient target rangesare achieved, the loop controller may place the controlled medicaltreatment device(s) back into a standard state. A standard state will bedifferent for each medical treatment device and likely also differentfor each patient. Patient parameter target ranges will likewise also bedifferent for each patient, and also for patient status. For example,the respirator rate target range may be different depending on whetherthe patient is sedated.

Embodiments of the technology may also automatically adjust intravenousfluid or drug infusion rates based on feedback from the cardiac outputor respiratory rate sensed. In one such embodiment, a patient-controlledanalgesia pump may be deactivated if a respiratory rate drops too low.Respiratory depression can be fatal in this group and this safeguardwould prevent overdose. An automated feedback system may also beadvantageous in a large volume resuscitation procedure, wherein fluidinfusion can be tailored based on intraabdominal pressure to preventabdominal compartment syndrome by sounding an alert and slowing infusionrates as the intraabdominal pressure rises. Yet another automatedfeedback feature may provide direct feedback to a ventilator system toprovide the optimal pressure of ventilated gas. In the setting ofincreased abdominal pressure, typical ventilator settings do not providesufficient respiration for the patient. An automated adjustment of theventilator settings based on intraabdominal pressure feedback from thisembodiment may advantageously provide for optimal patient ventilation.Embodiments of the technology may also be applied as a correction in theapplication or understanding of other diagnostic measurements. Forexample, central venous pressure may be dramatically distorted in thesetting of elevated intraabdominal pressure. Providing direct access tothese data by the central venous pressure reporting system allows forthe automatic correction and accurate reporting of this criticalphysiologic parameter. Embodiments of the technology may also be used ina variety of other ways to automate therapy including infusion of fluidsthat may further include active agents, such as pressors or diuretics inresponse to increased or decreased cardiac output or other parameters.

In addition to directly controlling medical treatment device(s), loopcontroller 2928 may also sound alarms, including audible alarms, emailedalarms, texted alarms, pager alarms, etc. Loop controller 2928 may alsoprovide output to other systems for system integration, such asoutputting information to an Electronic Health Record or other dataarchiving system, or other systems. Loop controller 2928 may alsoreceive inputs from various EHR, EMR, or other systems.

Medical treatment may be administered to the patient as a result of datacollected by and/or analyzed by, the sensing Foley catheter system. Thistreatment may be a medication administered automatically, via a loopcontroller, or it may be administered manually, via traditional drugmethods, i.e. orally, injection etc.

Further medical diagnoses may also be performed based on the results ofthe sensing Foley catheter system.

Specific Gravity

Urine specific gravity may be measured using pressure and ultrasoundmeasurements using a Sensing Foley Catheter. FIG. 34 shows a plotillustrating how ultrasonic and pressure measurements of volume divergewith liquid density. The liquid being measured is synthetic urineconcentrate, with a specific gravity of around 1.100.

For a liquid with specific gravity of 1.000, the two measurementtechniques are calibrated to provide the same volume measurements.However, as density increases, they begin to diverge. With pressure, anincrease in density results in an increased volume reading, since V=A*hand P=ρ*g*h, or V=A*ρ*g/P. With ultrasound, an increase in densityresults in a decreased volume reading, since V=A*h, v=h*2/t, andv=(E/ρ){circumflex over ( )}(1/2), so V=A*(E/ρ){circumflex over( )}(1/2)*t/2.

V: volume

A: cross-sectional area

h: height of liquid

P: pressure

ρ: liquid density

g: gravity

v: speed of sound

t: time for sound to reflect

E: bulk modulus elasticity of liquid

In simpler terms, as the liquid increases in density, the pressureincreases and skews that measurement high. At the same time, the soundtravels faster and skews the ultrasound measurement low. By measuringhow much they have diverged, the density of the liquid can bedetermined. This assumes the temperature is not changing, however,temperature can also be monitored to correct for temperaturevariability. Volume measurements via ultrasound and pressure can beperformed with a Sensing Foley Catheter, as can temperaturemeasurements. In this way, a Sensing Foley Catheter in combination witha controller can determine urine specific gravity.

Reducing Condensation

Balloon catheters, especially balloon catheters that are designed toreside in a human or animal body for relatively long periods of time,may leak over time. For example, a balloon inflated with air or anothergas, may leak air out of the balloon over time. Alternatively, a balloonfilled with a liquid may leak liquid out over time. The opposite is alsotrue. A balloon filled with gas or air which resides in fluid, such asurine, blood etc., may experience leakage of the fluid into the balloonover time. This is particularly true if the balloon is inflated at arelatively low pressure.

A sensing Foley catheter is an example of a balloon which is designed tobe inflated for relatively long periods of time and at relatively lowpressures. In this example, where a balloon is designed to measurepressure, the balloon may be inflated at a relatively low pressure andas a result, may be manufactured out of a relatively soft and thinmaterial. Because of the low inflation pressure and soft thin balloonmaterial, it is possible that liquid may leak into the balloon overtime. Liquid in a pressure measuring balloon can adversely affect verysensitive pressure measurements, particularly if the liquid migratesinto the catheter lumen through which the pressure measurements aretaken.

One embodiment to solve this problem is to place a very small porefilter, or hydrophobic filter, between the pressure measuring balloon,and the pressure measuring lumen of a catheter. This allows the balloonto be inflated, and continually primed to maintain its pressure, as wellas pressure measurements to be taken via the catheter lumen. Air or gascan pass through the filter, but fluid cannot.

Another embodiment comprises making a balloon out of a low moisturepermeability material.

Another embodiment comprises refreshing the gas within the balloon byalternatively applying vacuum and pressure to the balloon, eitherthrough one lumen, or more than one lumen.

Another embodiment comprises circulating the gas within the balloon byhaving more than one lumen access the balloon. One lumen may be used tointroduce gas into the balloon and another lumen may be used to pull gasfrom the balloon.

Another embodiment includes using a desiccant within the balloon, theballoon lumen, the gas supply to the balloon, or any combination ofthese.

FIG. 35 shows the distal end of a Foley type balloon catheter which maybenefit from condensation reduction. In this example, the ballooncatheter is designed to be placed in the bladder of a patient to aid indraining urine from the bladder. The catheter has a retention balloon3506 which anchors the catheter within the bladder. Catheter shaft 3502contains the lumens of the catheter. Opening 3504 allows urine fromwithin the bladder to drain through the catheter and exit the proximalend of the catheter (not shown). Opening 3508 is for inflating anddeflating the retention balloon. Pressure sensing balloon 3510 isinflated and deflated via opening 3512. Pressure sensing balloon 3510transmits pressure signals from within the bladder through a pressurelumen within the catheter shaft and to a pressure transducer proximal tothe proximal end of the catheter.

Under certain circumstances, over time, fluid may leak into pressureballoon 3510. In addition, fluid may migrate from within pressureballoon 3510, through opening 3512 and into catheter shaft 3502. Fluidinside the pressure lumen may adversely impact pressure readings fromthe pressure balloon. As a result, it is desirable to prevent fluid frommigrating from within the pressure balloon through opening 3512, or, ifpossible, to reduce the amount of fluid from entering into the pressureballoon.

FIG. 36 shows an embodiment of a filter within a balloon. Filter 3602resides between the interior of balloon 3510 and the pressure lumeninside of the catheter at opening 3512. Filter 3602 is preferably madeof a material which allows gas to pass through it, but not fluid. Forexample, a filter may be made from a hydrophobic membrane such asVersapor, PTFE, ePTFE. The filter may be made out of a polymer, such asNylon, or any other suitable material. The pore size may be around 3microns, or may be around 5 microns or may range from around 0.2 micronsto around 5 microns, or may range from around 5 microns to around 10microns. The thickness of the filter may range from around 6 mils toaround 12 mils. Alternatively the thickness of the filter may range fromaround 1 mil to around 6 mils. The pore size is related to the balloonsensitivity. For example, a 5 micron pore size filter may be appropriatefor a balloon inflated to around 5 mm Hg to around 20 mm Hg, with theability to sense pressure differences down to the 0.01 mm Hg resolutionrange. A smaller pore filter may be used if pressures measured via apressure balloon may be less sensitive. A larger pore filter may be usedif pressures measured via a pressure balloon need to be more sensitive.

FIG. 36 shows a filter in the form of a tubing which encircles thecatheter shaft at opening 3512, completely covering the opening. Thefilter may be adhered at its ends to the catheter shaft using anysuitable adhesive or other means, such as heat shrinking. The sealbetween the filter and the catheter is ideally gas impermeable so thatgas entering and exiting balloon 3510 via opening 3512 must pass throughfilter 3602.

FIG. 37 is another embodiment of the present invention which comprises asmaller catheter shaft where the filter is attached within the balloon.Catheter shaft 3704 within the balloon is a smaller diameter thancatheter shaft 3706 which is not under the balloon. This prevents theadded bulk of filter 3702 from increasing the diameter of the deflatedballoon.

FIG. 38 shows the embodiment shown in FIG. 37 with the balloon deflatedand it can be seen that the reduced diameter of the catheter shaft underthe balloon area prevents a significant bulge in the balloon catheter.

FIG. 39 shows another embodiment of a filter under a balloon. Filter3902 in this embodiment does not go all the way around the shaft of thecatheter, but is instead a flat or curved piece of filter which isadhered to the catheter shaft via adhesive or other suitable means. Theadhesive preferably seals the filter all the way around its edgeswithout infringing on the balloon inflation/deflation/pressure measuringopening 3512.

FIG. 40 shows another embodiment of a filter 4002 where the filter isshorter in length.

FIG. 41 shows another embodiment of a balloon catheter with filter. Inthis embodiment, the balloon catheter has 2 lumens in fluidcommunication with the balloon. Filter 4102 is covering opening 4104while opening 4106 is uncovered. In this embodiment, openings 4104 and4106 may each access separate lumens of the catheter, or the same lumen.In the embodiment where they access separate lumens, balloon inflation,deflation, and pressure measurements may be performed via either lumen.For example, pressure measurements may be taken via the lumen in fluidcommunication with opening 4106 until liquid buildup in the lumenadversely affects the pressure measurements. At this point, the pressuretransducer may be switched to the lumen in fluid communication withopening 4104 so that pressure measurements may be taken through a lumenclear of liquid.

Alternatively, pressure measurements may be taken via the lumen in fluidcommunication with opening 4106 until liquid buildup in the lumenadversely affects the pressure measurements. At this point, gas may beintroduced into the lumen in fluid communication with opening 4106 toclear the lumen of fluid. Simultaneously, the gas may be pulled from theballoon via the lumen in communication with opening 4104. In this way,liquid can be cleared from the lumen in communication with opening 4106and pressure measurements may be resumed through that lumen. This lineclearing procedure can be programmed to take place on a periodic basis.

FIG. 41 shows the two balloon openings 4102 and 4106 on different sidesof the catheter with filter 4104 only covering one of the openings.Alternatively, FIG. 42 shows an embodiment similar to that of FIG. 41,except that the 2 openings, 4204 and 4206, may be side by side, wherefilter 4202 only covers one of the openings.

FIG. 43 shows an embodiment of the present invention where filter 4302covers larger opening 4304. A larger opening may be desirable to obtainmore accurate pressure measurements from the balloon. In addition, alarger opening may be possible with the addition of filter 4304 becauseof the extra integrity that the filter, and possibly its adhesive means,provides to the area of the catheter around opening 4304.

FIG. 44 shows an embodiment of the present invention where filter 4402is attached to the catheter shaft via heat shrink tubing segments 4404.This allows a gas-tight seal between the filter and the catheter whileensuring that the catheter opening 4406 remains clear.

FIG. 45 shows an embodiment similar to that of FIG. 44 where thecatheter shaft is reduced under the balloon area. This allows theballoon to deflate without causing a bulge on the catheter where thefilter is attached. Filter 4502 is attached to the catheter shaft viaheat shrink tubing segments 4504. This allows a gas-tight seal betweenthe filter and the catheter while ensuring that the catheter openingremains clear.

FIG. 46 shows an embodiment of the present invention where filter 4602is attached to the inside of the catheter at the opening.

FIG. 47 shows an embodiment of the present invention where the balloonhas two access lumens, 4702 and 4704. In this embodiment, the ballooncatheter has two lumens in fluid communication with the balloon. In thisembodiment, openings 4702 and 4704 may each access separate lumens ofthe catheter, or the same lumen. In the embodiment where they accessseparate lumens, balloon inflation, deflation, and pressure measurementsmay be performed via either lumen. For example, pressure measurementsmay be taken via the lumen in fluid communication with opening 4702until liquid build-up in the lumen adversely affects the pressuremeasurements, or up until a set period of time. At this point, gas maybe introduced into the lumen in fluid communication with opening 4702 toclear the lumen of fluid. Simultaneously, the gas may be pulled from theballoon via the lumen in communication with opening 4704. The inversecan also be done—fluid may be introduced into the lumen in fluidcommunication with opening 4704 and removed from the lumen in fluidcommunication with opening 4702. In this way, liquid can be cleared fromthe lumen in communication with opening 4702 and pressure measurementsmay be resumed through that lumen. This line clearing procedure can beprogrammed to take place on a periodic basis. Openings 4702 and 4704 areshown here opposed to each other, but the openings may be staggered.

FIGS. 48 and 49 show two different pressure balloon designs, althoughany suitable design and/or shape may be used. Depending on the balloonmaterial, a balloon may be manufactured in different ways. Somematerials are better suited to blow molding while some are better suitedto dip molding. Other manufacturing techniques, for example, resistiveheat sealing, may be used as well. FIG. 48 shows an example of a blowmolded balloon. FIG. 49 shows an example of a dip molded balloon.

Some examples of materials from which a balloon may be manufacturedinclude urethane, polyurethane, polyethylene, Nylon, polyvinylidenefluoride, or any other suitable polymer or other material or anycombination of materials.

Balloon coatings may also be utilized to reduce fluid permeability ofthe balloon. An example of such a coating is poly(p-xylylene) polymer,or Parylene.

In some embodiments, it is desirable to prevent any moisture vapor fromentering the pressure balloon. In these embodiments a water, or fluid,impermeable material may be used for the balloon. Some of the materialsmentioned herewithin are suitable. In addition, Biaxially-orientedpolyethylene terephthalate (BoPET), often going by the brand name,Mylar, may be used. Also a metalized polymer or any other suitablematerial may be used.

In some embodiments, the sensing Foley type catheter is configured toreport the presence of a water droplet or other obstruction in anair-filled lumen (such as the pressure lumen), and then handle orresolve the droplet. In a hypothermic setting, in particular, moisturein an air lumen can condense and form obstructive water droplets. Waterdroplets in an air-filled lumen (or air bubbles in a water-filled lumen)can disturb or complicate pressure signals due to the surface tension ofthe water. Accordingly, a pressure-transmission lumen in someembodiments of the disclosed technology may include a hydrophilicfeature (such as a coating on the wall of the lumen itself, or ahydrophilic fiber running the length of the lumen) to wick moisture awayfrom the lumen in order to maintain a continuous, uninterrupted airchannel. In some embodiments, a hygroscopic composition (silica gel, forexample) may be used in line with the air infusion line or within theair infusion lumen itself to capture water or humidity. In someembodiments, a hygroscopic composition may be included within thecatheter so that the air infusion circuit need not be serviced toreplace this material.

In some embodiments, desiccated air or gas may be used in the pressurelumen and pressure balloon to prevent moisture accumulation.

In some embodiments a hydrophobic or hydrophilic coating may be used inthe pressure lumen and/or pressure balloon.

Gas Content

Another embodiment includes using a hydrophobic filter or membrane as aninterface with the urine in the bladder, or the mucosal lining of theurethra, to measure relative oxygen, or other gas, content of the urineor tissue.

In some embodiments of the sensing Foley catheter, it is desirable tomeasure the gas content tissue and/or urine or changes in gas contentover time. Potential gasses of interest include oxygen, carbon dioxide,nitrogen, gases associated with anesthesia or other gasses. In someembodiments the membrane is permeable to gas, but not to liquid, forexample, a hydrophobic membrane, or other suitable membrane, may beused. The pore size of the hydrophobic membrane may be around 5 microns.Alternatively, the pore size of the hydrophobic membrane may be about 3microns to about 7 microns.

FIG. 50 shows a sensing Foley catheter with an oxygen permeablemembrane. Retention balloon 5002 is in fluid communication withinflation/deflation port 5010. Urine flows through opening 5004 throughthe catheter and out of port 5012 which is in fluid communication withopening 5004. Pressure sensing balloon 5006 is in fluid communicationwith lumen 5014. Gas permeable membrane 5008 is covering an opening atthe distal end of the catheter which is in fluid communication withlumens 5016.

FIG. 51 shows a sensing Foley catheter with an oxygen permeable membranewhich is similar to that shown in FIG. 50 except that membrane 5108 isbetween pressure sensing balloon 5106 and retention balloon 5102.Opening 5104 for urine may be placed anywhere distal to retentionballoon 5102.

FIG. 52 shows an embodiment of a sensing Foley catheter where membrane5204 is incorporated into gas sensing balloon 5202. In this figure, gassensing balloon 5202 is distal to pressure sensing balloon 5206, howeveranother embodiment is shown in FIG. 53 where this is not the case. Gassensing balloon 5202 may be made out of silicone, polymer, or any othersuitable material.

The membrane material may be similar to hydrophobic membrane materialsdescribed in other embodiments herein. The membrane is permeable togasses, or to particular gas or gasses, but not to liquids, such asurine. In this way, gasses can pass through the membrane and into thecatheter for measurement of gas content of the tissue and/or urine,and/or changes in gas content over time. Gasses measured include oxygen,nitrogen, carbon dioxide, or other gasses.

The catheter may be placed in the patient such that the membrane is ineither the bladder or in the urethra. The membrane is shown here on asensing Foley catheter with a pressure sensing balloon, but the gaspermeable membrane may be placed on any body dwelling catheter,including catheters that reside in blood vessels or other body cavities.The membrane may be in direct or indirect contact with fluid, gas, orbody tissue.

FIG. 54 shows a controller which controls the measurements of oxygen orother gas(es). The controller will generally be external to the patientand connect to the catheter via ports, for example, ports 5016. Thecontroller may also control the pressure sensing function or otherfunctions of a sensing Foley catheter, or it may be a separatecontroller.

Gas measuring controller 5402 is shown here along with a representationof a catheter 5404 and gas transfer membrane 5406. Gas measuringcontroller 5402 includes air, or gas, inlet 5408, air, or gas, exhaust5410, pump 5412, oxygen, or other type of sensor 5414 and check valves5416.

In this embodiment, pump 5412 periodically pushes small amounts of air,or other gas, through tubing into the catheter. Air passes membrane“window” 5406 and the oxygen content of the air changes based on theoxygen content of mucosal lining (if gas transfer membrane is in theurethra) or urine (if gas transfer membrane is in the bladder). Furtherdownstream (back in gas measuring controller box 5402) the oxygenpercentage of the air is measured using a fiber optic, or other type of,oxygen sensor. The pump may only operate for short periods of time toallow air in the system time to equilibrate with the tissue/fluid.

Check valves 5416 help limit mixing of air that has passed through thesystem with outside air or air from an earlier measurement interval.

Measured oxygen, or other gas, content may be very small. Measurementsmay indicate either absolute gas levels or relative gas levels. Forexample, gas measuring controller measurements may show relative oxygencontent in the patient over time to indicate a change in the status ofthe patient.

FIG. 55 shows a schematic of how the gas measuring controller interactswith the catheter to measure gas content of the urine or patient tissue.Catheter 5502 includes urine draining lumen 5504 as well as gasmeasurement lumens 5506 and 5508, which are in fluid communication withgas transfer membrane 5510. Lumen 5506 contains air, or other gas,entering the catheter and lumen 5508 contains air, or other gas, exitingthe catheter after the carrier gas has passed the gas transfer membrane.The oxygen, or other gas, level in the exiting gas is measured todetermine oxygen levels or oxygen level changes in the urine and/ortissue of the patient. The incoming gas measurement lumen 5506 may beopen to atmospheric air, or other source, or it may be a closed system,so that the gas within lumens 5506 and 5508 is continuously circulatedso that the gas content changes can be readily determined over time. Inother words, air, or gas, inlet 5408, and air, or gas, exhaust 5410 inFIG. 54 may be fluidly connected to each other.

Where the incoming gas measurement lumen 5506 is open to atmosphere, thepump may be run intermittently so that the gas within the gas measuringlumens has more time to equilibrate across the membrane surface. Thisresults in a higher intermittent concentration of the measured gas andtherefore a more sensitive measurement.

The pump may be run continuously or intermittently regardless of whetherthe system is closed or open, but may result in more sensitivemeasurements if it is run intermittently in the open system mode. In theclosed system mode, trends may be more apparent as the measured gaswithin the system equilibrates with the gas level of the urine, fluid,or tissue being measured.

In this embodiment the urine lumen and the gas measurement lumens areseparate. However, the gas transfer membrane may also be situatedbetween the urine lumen and a gas measurement lumen as shown in FIG. 56,where gas transfer membrane 5602 is in fluid communication with theurine lumen.

FIGS. 57A and 57B show embodiments of a gas measuring add-on component.Gas measuring component 5702 may be inserted between the sensing Foleycatheter 1000, or any Foley catheter, and the urine drainage tube 1001,or any urine drainage tube. Gas measuring component 5702 includeshydrophobic filter 5704, which may be made of materials disclosedelsewhere herein. Gas inlet lumen 5706 and gas outlet lumen 5708 allowgas to pass over filter 5704 which is in gas communication with theurine within the drainage system. The air, or gas, near filter 5704 veryquickly becomes equilibrated with the gases within the urine within thedrainage system. FIG. 57B shows the path of air flow across filter 5704.Gas outlet lumen 5708 is in fluid communication with a controller (notshown here) which analyzes the gas within the lumen for the relevant gasor gasses. Gas inlet lumen 5706 may be open to atmosphere, another gas,or may be in a closed loop with gas outlet lumen 5708 within thecontroller. The controller may be the same controller which measuresurine output, mentioned elsewhere herein, or may be a separatecontroller. Lumens 5706 and 5708 may be incorporated into drainage tube1001 or may be separate. Gas measuring component 5702 may be a separatecomponent, as shown here, or may be incorporated into vent barb 1016.Gas measuring component 5702 may alternatively be located anywhere inthe system.

Detecting/Determining Certain Conditions

FIG. 58A shows a table that lists combinations of parameters that allowfor a fingerprint or signature (combination of parameters) for thedifferent indicators of AKI (pre-renal, intrinsic and obstructive). Inaddition, there may be a fingerprint or signature with respect to thetiming of changes of the parameters, which may also determine the causesof AKI (e.g. it is plausible that some parameters change faster forintrinsic AKI caused by glomerulonephritis versus intrinsic AKI causedby acute tubular necrosis). This multi-parametric approach may alsofacilitate the choice of effective therapies to treat AKI sincedifferent causes of AKI have different effective therapies (e.g.recombinant alkaline phosphatase is effective at treating intrinsic(septic) AKI but ineffective at treating non-septic AKI).

FIG. 58B shows a table that lists combinations of parameters that allowfor a fingerprint or signature (combination of parameters) for thedifferent indicators of sepsis, AKI, and acute respiratory distresssyndrome (ARDS). These signatures involve the increase, decrease, orboth of various patient parameters including urine output, heart rate,respiratory rate, temperature, stroke volume, cardiac output, andabdominal perfusion pressure. Abdominal perfusion pressure is the meanarterial pressure (MAP) minus intra-abdominal pressure (TAP). Meanarterial pressure is equal to the diastolic pressure (DP) plus 1/3 ofthe pulse pressure (PP). (The pulse pressure equals systolic pressureminus diastolic pressure.) In short, MAP=DP+1/3PP

Other patient parameters may also be used. One, some, or all relevantparameters may be used by the controller to communicate a diagnosisand/or risk to the user or to another device. Patient parameterscaptured by the sensing Foley catheter system may be used on their own,or in conjunction with parameters obtained elsewhere, such as an EKG, ablood pressure measuring device, or info from an EMR.

The sensing Foley catheter system provides real-time, automatic, precisephysiological parameter monitoring for the early detection of variousmedical conditions. By utilizing real time multivariate (point value)and times series (trending) analyses of these high frequency datastreams to inform our machine learning-powered model, a highly sensitivephysiologic signature for early sepsis onset (or other medical conditiondetermination) may be developed. This will improve clinical outcomes byenabling earlier diagnosis and intervention. The signatures relating tothe data relating to the physiologic changes that occur prior to and/orduring the onset of certain medical conditions can be continuouslyimproved using machine learning via artificial neural networks tostrengthen the relevant parameters, weaken the less relevant parametersand build or destroy connections. This will enable the controller toutilize algorithm to distinguish medical conditions from one another andfrom normal and other pathologies.

Some embodiments of the present invention may measure urine outputimmediately after the patient has been given a diuretic. This type oftest can be a strong indicator of whether a patient with AKI willprogress to a more severe stage and/or die. If a patient's urine outputincreases after administration of the diuretic, this indicates that thepatient is less likely to progress to a more severe stage of AKI. If apatient's urine output does not significantly increase afteradministration of the diuretic, this indicates that the patient is morelikely to progress to a more severe stage of AKI. The present inventionis able to quickly and accurately measure urine output in real time.Therefore the response to the diuretic can be detected more quickly(minutes rather than hours) than with traditional urine measurementtechniques.

This test can be automated with the controller which provides acontrolled dose of a diuretic, and then monitors the urine output overminutes, or hours, preferably only minutes. The diuretic given may befurosemide, or any other suitable loop diuretic or other diuretic. Thediuretic may be given, and data collected, as disclosed in Chawla L S,Davison D L, Brasha-Mitchell E, Koyner J L, Arthur J M, Tumlin J A, ShawA D, Trevino S, Kimmel P L, Seneff M G. Development and standardisationof a furosemide stress test to predict the severity of acute kidneyinjury. Crit Care. 2013 Sep. 20; 17(5):R207, herein incorporated byreference.

In addition to detecting AKI, the present invention is capable ofdetecting urinary tract infections (UTIs), as indicated by decreasingoxygen tension, carbon dioxide levels, increasing specific gravity, andrelatively stable urine output and conductance. The detection of UTI canbe achieved in the absence of AKI, and possibly in the presence of AKI,by combining urinary markers for a unique fingerprint of UTI. The uniqueUTI fingerprint can alert clinicians to the presence of UTI.

In addition to detecting AKI and UTI using the described parameters,these parameters may be used in combination with intra-abdominalpressure (TAP), respiratory rate (RR), heart rate (HR), cardiac output(CO), relative stroke volume (RSV), temperature (Temp), pulse pressure(PP), urine conductance (UC), urine output (UO) and/or stroke volume(SV) readings, which are already used for detecting conditions such asintra-abdominal hypertension (IAH), abdominal compartment syndrome (ACS)and sepsis. Adding IAP, RR, HR, CO, RSV, Temp, PP, UC, UO and/or SVmeasurements to the algorithm described herein may increase thesensitivity and specificity of detecting AKI or UTI. On the other hand,adding the measurements obtained by the present invention to an IAP, RR,HR, CO, RSV, Temp, PP, UC, UO and/or SV measurement algorithm mayincrease the sensitivity and specificity of detecting IAH, ACS orsepsis. Other clinical applications include the treatment of trauma andburns.

In addition to absolute measurements of IAP, RR, HR, CO, RSV, Temp, PP,UC, UO, gas concentrations and/or SV, trending data of these parametersmay also be used to detect IAH, ACS, sepsis or other conditions. Forexample, the slope of values of these parameters over time, and/or thevariability of values of these parameters over time may also be used.Another example of using data trends is the use of pulse pressurewaveform analysis and pulse wave velocity (or pulse transit time). Pulsetransit time can be determined by capturing a cardiac signal, such asthe EKG, from leads on the sensing Foley catheter, and/or elsewhere, anddetermining the time that a pulse wave pressure signal to travel to thebladder. Multiple parameters and/or parameter trends may be used todetermine the presence of IAH, ACS, sepsis or other conditions.

Some examples of using trending data include:

-   -   A decreasing UO in the setting of stable vitals (otherwise) may        indicate acute kidney injury. If stroke volume is decreasing,        then the kidney may be ischemic. If urine volume surges in the        setting of stable vitals, it may indicate toxic acute kidney        injury.    -   An increasing respiratory rate along with decreasing stroke        volume may indicate a pulmonary embolism, hemorrhage or other        volume depletion.

An increasing respiratory rate in the setting of stable vitals mayindicate an impending airway obstruction.

-   -   A decreasing respiratory rate in the setting of stability in        other parameters may indicate narcotic overdose. This is a big        problem with patient controlled analgesia.    -   Increasing intraabdominal pressure (IAP) in the setting of        stable stroke volume and increasing urine output may be an        indicator of impending fluid overload.    -   Increasing IAP with decreasing UO and decreasing cardiac output        may be an indicator of cardiorespiratory insufficiency. This may        be due to fluid overload, sepsis, etc.

The present invention can be used in a variety of hospital settings(e.g. emergency room, operating room, intensive care unit, ward). At anytime, the device may be used to monitor the progression of AKI, andwhether it is improving or declining Its algorithms work to alertclinicians to a newly developed case of AKI or to a change in the statusof AKI. The device may be placed before insult to the kidney occurs(e.g. patients undergoing cardiac surgery to detect if insult to thekidneys begins intra-operatively) in order to detect initiation of AKI.It may be placed when insult to the kidney injury is already present inorder to detect the degree of insult at that time. The device may alsobe used to monitor the response the therapy/therapeutic intervention(e.g. renal replacement therapy, fluid resuscitation).

Alternative Embodiments

Embodiments of the technology may also report patient movement in thedetection or diagnosis of seizure disorder. In this embodiment, thepressure variations may trigger an EEG or recording equipment to allowfor intense period of monitoring during an episode suspected of being aseizure. In addition, or alternatively, a pressure sensor, acousticsensor or other sensors may be used to detect bowel activity, includingperistalsis, patient movement, seizure activity, patient shivering,frequency of coughing, severity of coughing, sleep duration, sleepquality, speech detection, patient compliance (movement or lackthereof), and may alert the healthcare provider that the patient has notmoved and must be turned or rolled. This movement-related informationmay also be relayed to a hypothermia device, a drug delivery device orother device to control or mitigate seizure activity, shivering and/orcoughing.

In some embodiments, the sensing Foley type catheter is configured toreport the presence of a water droplet or other obstruction in anair-filled lumen (such as the pressure lumen), and then handle orresolve the droplet. In a hypothermic setting, in particular, moisturein an air lumen can condense and form obstructive water droplets. Waterdroplets in an air-filled lumen (or air bubbles in a water-filled lumen)can disturb or complicate pressure signals due to the surface tension ofthe water. Accordingly, a pressure-transmission lumen in someembodiments of the disclosed technology may include a hydrophilicfeature (such as a coating on the wall of the lumen itself, or ahydrophilic fiber running the length of the lumen) to wick moisture awayfrom the lumen in order to maintain a continuous, uninterrupted airchannel. In some embodiments, a hygroscopic composition (silica gel, forexample) may be used in line with the air infusion line or within theair infusion lumen itself to capture water or humidity. In someembodiments, a hygroscopic composition may be included within thecatheter so that the air infusion circuit need not be serviced toreplace this material.

In some embodiments of the disclosed technology, air may also beintermittently (and automatically) infused and extracted into thepressure-sensing balloon so that the balloon is in a constant state ofbeing optimally primed, as described in further detail above. In thecase of the wicking fiber or hydrophilic coating in the lumen, the airextraction may also contribute to removing and trapping any water fromthe air line. In the instance of a liquid-filled lumen, a hydrophilicfiber or a hydrophilic coating on the inside of the pressure lumen willprovide similar benefit in allowing this lumen to handle an air bubble.In this instance, an air bubble may distort the signal, but the airwater interface surface tension is defused by a hydrophilic coating inthe lumen of the catheter.

Additionally, a custom extrusion and lumen shape may also be used toprevent obstruction in the case of liquid and/or air-filled lumens. Insome embodiments of the technology, for example, a Foley type cathetermay have a lumen that is stellate in cross sectional profile. Such alumen is generally immune from obstruction by a water droplet, as thedroplet tends to cohere to itself and push away from the hydrophobicwalls. This behavior tends to disallow filling of a cross-sectionalspace, and allows for an air channel to remain patent around the waterdroplet and communicate to the sensor. The same logic applies to an airbubble in water in a hydrophilic, stellate water lumen. In this instancethe hydrophilic liquid will cling to the walls and allow for acontinuous water column that excludes the air bubble to the center ofthe lumen. The same applies for a hydrophobic liquid in a hydrophobiclumen. In some embodiments, the catheter may include an air channel, anda sensor incorporated within the catheter itself or a fluid lumen thatis capable of transmitting the pressure back to a sensor.

The drainage tube may be a multi-lumen tube to contain the urinedrainage line, the pressure lumen, and the wires of the thermocouple andis connected to the barb on one end and the controller on the other end.

The Foley catheter may be extruded with BaSO4 or have attachedradiopaque markers to provide fluoroscopic observation.

The thermistor located at the tip of the catheter may be fixed in placeusing a number of extrusion profiles and assembly techniques.

In some embodiments, the sensing Foley catheter may include a bloodpressure sensing element that may take any of several forms. In oneembodiment, a blood pressure sensing element includes a pressuredelivery balloon (either a separate, dedicated balloon or a balloon influid communication with a device retention balloon or a pressuresensing balloon) that can be optically analyzed as it is inflated todetermine at which pressure the vessels within the bladder or urethraare blanched and blood flow is stopped. This approach provides a readingof the perfusion pressure of the tissue abutting the pressure deliveryballoon, such reading reflective of both the systemic blood pressure andvascular resistance. This embodiment of a perfusion pressure device maybe used to provide early detection or monitoring of a variety of acuteor emergent medical conditions such as sepsis, shock, hemorrhage, andcan be particularly advantageous in detecting these conditions at anearly stage. In predicting sepsis, embodiments of the invention may becapable of receiving white blood cell count information to betterpredict sepsis.

Other modalities may be used to detect that the tissue has been blanchedor ischemic, as well, with the common methodological aspect being thatof the intermittent inflation within the lumen, body cavity or bodilytissues to provide the compression of the vasculature. Embodiments ofthis device and associated methods may also be used to detect perfusionpressure in other areas of the body with an intermittently inflatablemember and optical detection of blood flow or the presence of blood.

Tissue perfusion information may also be provided by way of sensorsdisposed on the shaft of the catheter such that they contact theurethral wall when the catheter is in place. These sensing technologiesmay include microdialysis, pyruvate, lactate, pO₂, pCO₂, pH, perfusionindex, near-infrared spectroscopy, laser Doppler flowmetry, urethralcapnography, and orthogonal polarization spectroscopy. Any of thesetests may also be performed on the urine or the bladder wall itself togenerate measurements of tissue perfusion.

Another embodiment of the sensing Foley catheter system includes anembodiment of the clearing mechanism including a device and/or port forpositive airflow near the start of the drainage line. The positiveairflow facilitates drainage by forcing urine to flow through thedrainage line. The positive airflow device may include a one-way valveat the end of the urine catheter that allows urine to only flow towardthe urine collection device, and prevents air from entering thecatheter.

In some embodiments, a urine clearing mechanism comprises a coating onthe inside of the urine drainage tube to reduce surface tension andfacilitate drainage. In one aspect, said coating is a hydrophobicpolymer, including but not limited to PTFE or FEP.

In yet another embodiment, the clearing mechanism comprises a tubularhydrophobic vent filter that can be inserted into the drainage lumen ofthe device such that air will be evacuated throughout its length. Asegmental hydrophobic vent can also be incorporated at set intervals toensure that air is evacuated from the tube as it passes these regions.In this embodiment, the hydrophobic vent will be interspaced at minimumof 1-2 foot intervals to prevent submersion of the vents in urine. Byproviding redundancy the multiple vent/filters prevent the failure ofany one filter/vent due to its submersion. In the ideal configurationthe vent will be a PTFE or ePTFE material and will be affixed with abarb and or grommetted into the tube at intervals to allow for easymanufacturability. In an alternative embodiment, the vent takes the formof a slit or spiral that runs the length of the drainage tube, therebyallowing air to escape the tube at any point. This prevents the drainagetube from being positionally dependent when preventing and/oreliminating airlocks.

In an alternative embodiment, air locks are prevented by means of anextendable drainage tube, which prevents pockets of air from forming inthe high portions of the tube and urine from gathering in the lowportions. An extendable tube prevents this from occurring by keeping thetube as straight as possible between the urinary catheter and thecollection bag. In one aspect, the extendable drainage tube is composedof multiple telescopic sections that can be extended or collapsed tomatch the distance from the patient to the collection bag. In anotheraspect, the drainage tube is pleated to form an accordion, which can beextended or collapsed or deformed as necessary. In yet another aspect,the tube is coiled. In yet another aspect, the drainage tube isretractable by means of a spring coil that wraps the tubing around awheel to achieve the appropriate length.

Relative cardiac output and relative tidal volume may also becalculated, based on the deflection of the pressure sensor and/or otherforce gauge. If sampled with sufficient frequency (e.g., 1 Hz orgreater), respiratory excursions can be quantified in a relative mannerto the amplitude of the excursions at the time of catheter placement.Larger excursions generally relate to heavier breathing, or in thesetting of an upward drift in the baseline, a higher peritonealpressure. The small peaks on the oscillating respiratory wave, caused bythe pumping heart, may be tracked as well by using faster sampling rates(e.g., 5 Hz or greater), and the amplitude of this wave may be used, inthe setting of a relatively constant peritoneal pressure, to determinethe relative cardiac output, in the setting of a known, stableperitoneal pressure, absolute stroke volume and/or cardiac output.

Intrabdominal pressure or bladder pressure, as sensed by an embodimentof the disclosed technology, may also be used to detect the level ofpatient movement (as may vary, for example, between substantially nomovement to a high level of movement) and to report the movement levelto a healthcare provider. A short burst of peaks and valleys in bladderpressure activity can serve as a proxy for body movement in that such abladder pressure profile is a strong indicator that the patient is usingtheir abdominal muscles, as, for example, to sit up or get out of bed.This embodiment may be of particular benefit for patients that are atrisk of falling. In a patient that is a fall-risk, a healthcare providermay be notified that the patient is sitting up and respond accordingly.Alternatively, the device may be used to report inactivity of a patientand/or lack of patient movement.

Pulse oximetry elements allow for a determination of blood oxygenconcentration or saturation, and may be disposed anywhere along theurethral length of the catheter. In some embodiments, the sensor orsensors are disposed within the tubing of the device to ensureapproximation to the urethral mucosa. With this technology, a healthcareprovider can decompress the bladder with a urinary catheter and obtainpulse oximetry data in a repeatable and accurate manner. The powersource for pulse oximetry may be incorporated within the urinarycollecting receptacle or within the catheter itself. In someembodiments, the pulse oximeter is reusable and the catheter interfaceis disposable; in this arrangement the pulse oximeter is reversiblyattached to the disposable catheter and removed when oxygen measurementsare no longer desired. Embodiments of the sensing Foley catheter mayinclude an optically transparent, or sufficiently transparent, channelfor the oximetry signal, such as a fiberoptic cable, transparent window,and an interface for the reusable oximeter. This method and device forurethral pulse oximetry may be used in conjunction with any of the otherembodiments detailed herein or may be a stand-alone device.

An antibacterial coating, or a material impregnated with ananti-bacterial compound, may be used on the sensing Foley catheter toprevent infection. Examples of antibacterial coatings/materials includesilver, silver citrate, Parylene, or any other suitable material.

Pulmonary Blood Volume Variability may also be determined by the sensingFoley catheter system to aid in assessing existence or risk of heartfailure. Reduced left ventricular function can lead to an increase inthe pulmonary blood volume (PBV) or a decrease in the pulmonary bloodvolume variation. PBV variation is defined as the change in PBV overtime during the cardiac cycle. PBV can be determined as a product of thecardiac output and the pulmonary transit time (PTT). Cardiac output canbe determined as the product of stroke volume and heart rate wherestroke volume is the area under the flow-time curve for one cardiaccycle. Pulse transit time may be obtained by looking at the delaybetween the QRS complex in an EKG vs. the appearance of the signal inthe bladder. The EKG signal may be obtained from a separate EKG lead, alead incorporated into the sensing Foley catheter, a lead incorporatedinto the catheter insertion kit, or elsewhere. An EKG lead may also beable to read the EKG signal from within the urine, anywhere in thesystem. 2 leads may be used to more accurately determine the pulsetransit time.

It has been found that stroke volume, ejection fraction, and PBVvariation decrease after myocardial infarction, and that the greatestchange is seen in PBV variation. Therefor determining PBV variation andidentifying a decrease in PBV variation may be a strong indication ofheart failure, or heart failure risk.

Data collected by the sensing Foley catheter system may be stored in adatabase and analyzed for trending or other uses. For example, data maybe collected from several patients and aggregated anonymously to be usedto better treat, monitor, or predict the behavior of future patients.For example, data collected over time relating to heart rate,respiratory rate, temperature infection etc., may be aggregated andanalyzed by the controller to find trends, such as the relationshipbetween or among the various parameters and results. For example,certain trends in temperature alone, or in combination with otherparameters, may be a predictor of infection, the onset of sepsis, ARDSand/or AKI. FIG. 58 shows some known examples, but other and currentlyunknown trends may emerge from the aggregated patient data.

Data collected by the sensing Foley catheter system may be integratedwith Electronic Health Records (EHRs) or Electronic Medical Records(EMRs) and/or other systems. Data collected by the sensing Foleycatheter system controller may directly or indirectly interface with anEMR/EHR system. Data, such as patient demographic, or medical historydata, from an EMR/EHR may also integrate with the sensing Foley cathetersystem.

Example of Data Processing System

FIG. 60 is a block diagram of a data processing system, which may beused with any embodiment of the invention. For example, the system 6000may be used as part of a controller as shown in several embodimentsherein. Note that while FIG. 60 illustrates various components of acomputer system, it is not intended to represent any particulararchitecture or manner of interconnecting the components; as suchdetails are not germane to the present invention. It will also beappreciated that network computers, handheld computers, mobile devices,tablets, cell phones and other data processing systems which have fewercomponents or perhaps more components may also be used with the presentinvention.

As shown in FIG. 60, the computer system 6000, which is a form of a dataprocessing system, includes a bus or interconnect 6002 which is coupledto one or more microprocessors 6003 and a ROM 6007, a volatile RAM 6005,and a non-volatile memory 6006. The microprocessor 6003 is coupled tocache memory 6004. The bus 6002 interconnects these various componentstogether and also interconnects these components 6003, 6007, 6005, and6006 to a display controller and display device 6008, as well as toinput/output (I/O) devices 6010, which may be mice, keyboards, modems,network interfaces, printers, and other devices which are well-known inthe art.

Typically, the input/output devices 6010 are coupled to the systemthrough input/output controllers 6009. The volatile RAM 6005 istypically implemented as dynamic RAM (DRAM) which requires powercontinuously in order to refresh or maintain the data in the memory. Thenon-volatile memory 6006 is typically a magnetic hard drive, a magneticoptical drive, an optical drive, or a DVD RAM or other type of memorysystem which maintains data even after power is removed from the system.Typically, the non-volatile memory will also be a random access memory,although this is not required.

While FIG. 60 shows that the non-volatile memory is a local devicecoupled directly to the rest of the components in the data processingsystem, the present invention may utilize a non-volatile memory which isremote from the system; such as, a network storage device which iscoupled to the data processing system through a network interface suchas a modem or Ethernet interface. The bus 6002 may include one or morebuses connected to each other through various bridges, controllers,and/or adapters, as is well-known in the art. In one embodiment, the I/Ocontroller 6009 includes a USB (Universal Serial Bus) adapter forcontrolling USB peripherals. Alternatively, I/O controller 6009 mayinclude an IEEE-1394 adapter, also known as FireWire adapter, forcontrolling FireWire devices.

Some portions of the preceding detailed descriptions have been presentedin terms of algorithms and symbolic representations of operations ondata bits within a computer memory. These algorithmic descriptions andrepresentations are the ways used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of operations leading to adesired result. The operations are those requiring physicalmanipulations of physical quantities.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the above discussion, itis appreciated that throughout the description, discussions utilizingterms such as those set forth in the claims below, refer to the actionand processes of a computer system, or similar electronic computingdevice, that manipulates and transforms data represented as physical(electronic) quantities within the computer system's registers andmemories into other data similarly represented as physical quantitieswithin the computer system memories or registers or other suchinformation storage, transmission or display devices.

The techniques shown in the figures can be implemented using code anddata stored and executed on one or more electronic devices. Suchelectronic devices store and communicate (internally and/or with otherelectronic devices over a network) code and data using computer-readablemedia, such as non-transitory computer-readable storage media (e.g.,magnetic disks; optical disks; random access memory; read only memory;flash memory devices; phase-change memory) and transitorycomputer-readable transmission media (e.g., electrical, optical,acoustical or other form of propagated signals—such as carrier waves,infrared signals, digital signals).

The processes or methods depicted in the preceding figures may beperformed by processing logic that comprises hardware (e.g. circuitry,dedicated logic, etc.), firmware, software (e.g., embodied on anon-transitory computer readable medium), or a combination of both.Although the processes or methods are described above in terms of somesequential operations, it should be appreciated that some of theoperations described may be performed in a different order. Moreover,some operations may be performed in parallel rather than sequentially.

Unless defined otherwise, all technical terms used herein have the samemeanings as commonly understood by one of ordinary skill in the medicalarts. Specific methods, devices, and materials are described in thisapplication, but any methods and materials similar or equivalent tothose described herein can be used in the practice of the presentinvention. While embodiments of the invention have been described insome detail and by way of illustrations, such illustrations are forpurposes of clarity of understanding only, and are not intended to belimiting. Various terms have been used in the description to convey anunderstanding of the invention; it will be understood that the meaningof these various terms extends to common linguistic or grammaticalvariations thereof. Further, while some theoretical considerations mayhave been advanced in furtherance of providing an understanding of thetechnology, the appended claims to the invention are not bound by suchtheory. Moreover, any one or more features of any embodiment of theinvention can be combined with any one or more other features of anyother embodiment of the invention, without departing from the scope ofthe invention. Still further, it should be understood that the inventionis not limited to the embodiments that have been set forth for purposesof exemplification, but is to be defined only by a fair reading ofclaims appended to the patent application, including the full range ofequivalency to which each element thereof is entitled.

Some embodiments of the sensing Foley catheter system include using UVlight, or light of an appropriate wavelength, to sterilize thecollection chamber itself or other components of the system. A UV lightsource may direct UV light through the walls of the collection chamber,or, alternatively, the UV light source may be located inside thecollection chamber. The UV light source may be used to sterilize thecollection chamber when the chamber is empty, full, or partially full.The UV sterilization process may happen continually, or intermittently.A UV light source may be located anywhere in the sensing Foley cathetersystem.

Spectroscopy—Spectrophotometry

Some embodiments of the sensing Foley catheter system include usinglight wavelengths in the range of around 520 nm to around 650 nm toidentify bacteria, red blood cells, and/or plasma/white blood cells. Seearea inside oval of FIG. 61.

Some embodiments of the sensing Foley catheter system include combiningspectrophotometry to identify white blood cells and bacteria incombination with identifying a decrease in PO2 and/or an increase in CO2to identify infection.

Some embodiments of the sensing Foley catheter system include thecontroller filtering the urine output data to compensate for increasedurine output immediately following the administering of a diuretic.Urine output generally increases immediately following theadministration of a diuretic. However in certain situations it isbeneficial to essentially ignore the increased urine output dataassociated with administration of a diuretic. The controller of thesensing Foley catheter system can automatically ignore the urine outputdata associated with the administration of a diuretic by identifying theshape of the urine output curve associated with the administration of adiuretic, and subtracting and/or ignoring the data associated with thisincrease. The identification of the curve shape may be done by slope,length of increase, amplitude of increase, shape, etc. Subtraction ofdiuretic induced urine output data may be beneficial in determining, orpredicting, the onset of AKI. See FIG. 62. For example, where urineoutput rises above about 2,000 ml/hour (peak), the controller mayidentify this as a situation where a diuretic has been administered.

Increased urine output caused by the administration of a diuretic can bedifferentiated from increased urine output caused by clamping, orotherwise blocking, of the urine drainage tube and/or Foley catheter. Inthe situation where the drainage lumen is clamped, urine output prior tothe increase will be essentially zero, or very low, for example lessthan 5 ml/hour. Contrastingly, in the situation of an administereddiuretic, urine output immediately prior to the administration of thediuretic may be very low, but will likely be above zero, for example,above about 5 ml/hour. In addition, in the situation where the drainagelumen is clamped, increased urine output following the unclamping of thedrainage lumen will be for a relatively short period of time, forexample, about 30 seconds to about 5 minutes. Contrastingly, in thesituation of an administered diuretic, increased urine output will befor a longer period of time, for example, about 30 minutes to about 2hours. In addition, in the situation where the drainage lumen isclamped, urine output following the unclamping of the drainage lumenwill likely be less than around 1000 ml. Contrastingly, in the situationof an administered diuretic, the urine output after the administrationof the diuretic will likely be more than about 1000 ml. Any or all ofthese factors may be used by the controller to analyze the urine outputvolume over time curve to determine when a diuretic has beenadministered and to subtract the increased urine output volumeattributable to the diuretic from the urine output presented to theuser.

In this way, the controller may automatically determine when a diureticis administered. Alternatively, the user interface of the controller mayinclude a button or other user input device (touch screen, voice controletc.) which indicates that a diuretic has been administered. Thecontroller will then look for an increased urine output and subtract theincreased urine output attributable to the diuretic from the urineoutput data presented to the user.

Some embodiments of the sensing Foley catheter system include thecontroller determining abdominal perfusion pressure (APP). APP isdefined as the difference between the mean arterial pressure and theintra-abdominal pressure (IAP). Mean arterial pressure can be determinedin conventional ways and combined with the controller's determination ofIAP to determine APP. The controller may further automatically alter theinfusion of fluids and/or pressors/vasopressors to increase or decreaseblood pressure.

Prevent Wetting of Filter/Vent

Some embodiments of the sensing Foley catheter system include one ormore vents and/or filters to prevent negative pressure from buildingwithin the Foley catheter and causing suction trauma to the bladder. Afilter/vent may be located at the junction of the Foley catheter and thedrainage tube or elsewhere, such as within the collection vessel or evenwithin the lumen of the drainage tube or Foley catheter themselves, aswill be described below.

The filter/vent in some embodiments is designed to repel fluids, i.e.from hydrophobic materials. However, despite using hydrophobicmaterials, the filter/vent can still be susceptible to wetting by fluid,especially urine. Some embodiments include a larger lumen, or lumenarea, where the filter/vent is located to reduce the likelihood that thesurface tension of the fluid causes the fluid to fill the lumen. FIG.63A shows a smaller diameter lumen where FIG. 63B shows a largerdiameter lumen in the vent/filter area. Note that when vent/filter 6304is facing upward or outward, the smaller lumen may still allow wettingof the filter/vent with fluid 6202, where a larger lumen may reduce thelikelihood of wetting of the filter/vent.

In embodiments in which the filter/vent is located at or near thejunction of the Foley catheter and the drainage tube, the area under ornear the filter/vent may be taped to the patient's leg to stabilize theFoley catheter once it is in place. The larger lumen tube helps preventwetting of the filter/vent in this situation, especially if thevent/filter is oriented away from the leg, so away from the patient. Insome embodiments the vent barb may be designed so that the vent/filteris facing outward when the barb or barb area is taped to the patient'sleg. For example, the barb may be curved, or attached to a curved base,as shown in FIG. 64, to better attach, and orient, to patient leg 6402.

In some embodiments the barb area may be elongated, for example between6 and 12 inches, with the vent/filter placed further from the patient,to allow the vent/filter to be placed easily in a location and manner toprevent wetting.

In some embodiments, vent/filters may be placed in multiple locationsaround the diameter of the draining lumen within the barb or elsewhere.Alternatively a vent may encircle all, or most, of the circumference ofthe lumen. In these embodiments, a reinforcing cuff or other structuremay surround the vent to provide structural integrity to the lumen.Filter/vents may also be placed along the length of the drainage tube.

The embodiment shown in FIG. 65 will also prevent wetting of thevent/filter. This embodiment includes vent tube 6502 with an inner lumenwhich connects to drainage lumen 6504 near barb area 6506, and is ventedto atmosphere, or other air/gas/fluid via one or more filter/vents 6508along the vent tube and/or near the other end. The filter/vent may be inthe collection vessel as is shown in FIG. 65, or may be elsewhere, suchas separate from the collection vessel.

A vent lumen may be incorporated into the drainage lumen, eitheralongside the urine drainage lumen, or within the urine drainage lumen.A vent lumen may alternatively be separate from the drainage lumen andconnected to the drainage lumen at a vent tube/drainage tube junction,for example, near barb area 6506.

The embodiment shown in FIG. 66 shows the sensing Foley catheter systemwith a positive pressure vent tube 6602 which has an inner lumen whichis in fluid communication with urine drainage lumen 6604 and pump 6606.The positive pressure vent tube may include filter 6612 anywhere alongits length, in-line or otherwise. The positive pressure vent tube mayinclude a vent at either end of the tube, anywhere along the tube, ormay include multiple vents.

The pump pulls a negative pressure on the urine drainage lumen andinstead of pumping the positive pressure into the atmosphere, thepositive pressure is pumped back into the urine drainage lumen via thepositive pressure tube. Alternatively, different pumps may be used forthe negative and positive pressures. In this way, an exact negative orpositive pressure can be controlled at the junction 6608 of the urinedrainage lumen and the positive pressure vent tube. Preferably, thepressure in junction 6608 is either slightly negative or neutral toprevent fluid flow from going back into the Foley catheter. For examplethe pressure in the junction may be maintained at about 0 mm Hg.Alternatively, the pressure in the junction may be maintained at about−2 mm Hg. Optional regulator 6610 may control the negative pressure withrespect to the positive pressure, by magnitude, timing, etc. Forexample, the regulator (which is controlled by the controller) mayimplement a slight delay so that negative pressure is pulled on theurine drainage line first, then at a set time later, or when aparticular negative pressure is achieved, positive pressure is appliedto the positive pressure tube and ultimate the positive pressuretube/drainage tube junction. This will prevent the net pressure at thepositive pressure tube/drainage tube junction from being positive andcausing urine to flow into the bladder rather than out of the bladder.The optional regulator may be in the form of a vent, of particulardimension (lower surface area or denser filter material for moreresistance, larger surface area or looser filter material for lessresistance). The positive pressure vent tube may connect to the urinedrainage lumen via a valve, such as an umbrella valve with a set crackpressure.

Alternatively, the positive pressure tube may be pressurized bycompressed sterile fluid/gas/air.

In addition, precise control of the negative pressure exerted on thebladder may allow for duplication of the normal filling and draining ofthe bladder. For example, a neutral, or zero, pressure may bemaintained, or even a slightly positive pressure may be maintained atthe base of the Foley for a period of time so that the bladder fillsnormally. Then, either after a set period of time, or after a certainpressure is reached (i.e., the pressure required to maintain a neutralpressure at the base of the Foley catheter), the pressure is reducedallowing for the bladder to empty, or drain. This process can becontrolled by the controller which controls the pressure regulator torepeat this process to emulate normal filling and emptying of thebladder.

In some embodiments, a valve may be used at the base of the Foleycatheter to better control the pressure in that area, including pressure(negative or positive) exerted on the bladder.

Note that the positive pressure tube embodiments may be used with any ofthe sensing Foley catheter system embodiments, including those withdifferent filter/vent configurations than those shown herein. Inaddition, any of the anti-airlock embodiments may be used with aregular, i.e. non-sensing, Foley catheter, or other catheters ordrainage tubes.

FIGS. 67-86 show magnifications of the barb area, X, of FIG. 66 to showexamples of different embodiments of this area.

In the embodiment shown in FIG. 67, valve 6702, such as an umbrellavalve with a set crack pressure is shown between the lumen of positivepressure vent tube 6602 and the urine drainage lumen 6604. The valve maybe a one-way valve. Vent 6704 is shown between the positive pressurevent tube and the atmosphere. Configurations may also exist where onlythe vent, or only the valve are present. Opening 6706 is in fluidcommunication with urine drainage lumen 6604 and chamber 6714 (withvalve 6702 periodically cutting off fluid communication to the chamber).Chamber 6714 is in fluid communication with the lumen of positivepressure vent tube 6602. Periodically, or continuously, positivepressure is applied through positive pressure lumen 6702 and/or negativepressure is applied to urine drainage lumen 6604. When the crackpressure of valve 6702 is exceeded, fluid, preferably gas, flows throughvalve 6702 and through opening 6706 and through the lumen of urinedrainage lumen 6604. This serves both to clear the line of airlocks orany blockages, and to clear chamber 6714 of any fluid, which reduces thelikelihood of vent 6704 becoming wetted. It also serves to clear vent6704 if it has been wetted. The crack pressure of valve 6702 refers tothe pressure differential between positive pressure lumen 6702 and urinedrainage lumen 6604. If the pressure in the urine drainage lumen isbelow the pressure in the positive pressure lumen by the crack pressure,the valve opens allowing fluid to flow from the positive pressure lumen,through the chamber, through opening 6706 and through the drainagelumen. For example, the crack pressure may be less than about 1 mm Hg.Alternatively the crack pressure may be less than about 2 mm Hg.Alternatively the crack pressure may be less than about 3 mm Hg.Alternatively the crack pressure may be less than about 4 mm Hg.Alternatively the crack pressure may be less than about 5 mm Hg.Alternatively the crack pressure may be less than about 10 mm Hg.

The pressure in the urine drainage lumen may periodically or continuallybe about −5 mm Hg. Alternatively, the pressure in the urine drainagelumen may periodically or continually be about −7 mm Hg. Alternatively,the pressure in the urine drainage lumen may periodically or continuallybe about −10 mm Hg. Alternatively, the pressure in the urine drainagelumen may periodically or continually be about −15 mm Hg. Alternatively,the pressure in the urine drainage lumen may periodically or continuallybe about −20 mm Hg. Alternatively, the pressure in the urine drainagelumen may periodically or continually be about −25 mm Hg. Alternatively,the pressure in the urine drainage lumen may periodically or continuallybe about −30 mm Hg.

The positive pressure in the positive pressure lumen may periodically orcontinually be about 5 mm Hg. Alternatively, the positive pressure inthe positive pressure lumen may periodically or continually be about 7mm Hg. Alternatively, the positive pressure in the positive pressurelumen may periodically or continually be about 10 mm Hg. Alternatively,the positive pressure in the positive pressure lumen may periodically orcontinually be about 15 mm Hg. Alternatively, the positive pressure inthe positive pressure lumen may periodically or continually be about 20mm Hg. Alternatively, the positive pressure in the positive pressurelumen may periodically or continually be about 25 mm Hg. Alternatively,the positive pressure in the positive pressure lumen may periodically orcontinually be about 30 mm Hg.

A vent may also, or alternatively, be present elsewhere along thepositive pressure vent tube, for example, close to the pump, or as partof a pressure regulator. A second vent/valve assembly 6708 is shown onthe barb in FIG. 67, however this second vent/valve assembly may or maynot be present. Optional thermistor 6710 and optional pressure lumen6712 are also shown. The positive pressure vent tube may alternativelybe exposed to atmospheric pressure.

FIG. 68 shows an embodiment of the barb area which includes vent 6802,valve 6804 and a small cross sectional area 6806 which is large enoughto allow air/gas to flow freely from the vent to the urine drainagelumen, but small enough to prevent liquid flow to the vent. For examplenarrowed portion 6806 may be less than about 1 mm in diameter.Alternatively, the narrowed portion may be less than about 2 mm indiameter. Alternatively, the narrowed portion may be less than about 3mm in diameter. Alternatively, the narrowed portion may be less thanabout 4 mm in diameter. The narrowed portion may be about 1-5 mm inlength. Alternatively, the narrowed portion may be about 5 mm-30 mm inlength. The embodiment shown in FIG. 68 may or may not include apositive pressure tube—it is shown without a positive pressure tube(i.e. exposed to atmosphere). This embodiment may or may not include thevalve.

FIG. 69 shows an embodiment of the barb area which includes vent 6902and a long vent tube 6904 which allows air/gas to flow freely from thevent to the urine drainage lumen, but is long enough to prevent liquidflow to the vent. For example, vent tube portion 6904 may be about 1-10mm in diameter and may be about 1-10 cm in length. For example, the venttube portion 6904 may be over about 2 cm in length. Alternatively, thevent tube portion 6904 may be over about 4 cm in length. Alternatively,the vent tube portion 6904 may be over about 10 cm in length. Theembodiment shown in FIG. 69 may or may not include a positive pressuretube—it is shown without a positive pressure tube. This embodiment mayor may not include a valve.

FIG. 70 shows an embodiment of the barb area which includes vent 7002and a long tortuous vent tube 7004 which allows air/gas to flow freelyfrom the vent to the urine drainage lumen, but is tortuous enough toprevent liquid flow to the vent. For example, vent tube portion 7004 maybe a coil. The embodiment shown in FIG. 70 may or may not include apositive pressure tube—it is shown without a positive pressure tube.This embodiment may or may not include a valve.

FIG. 71 shows an embodiment of the barb area which includes vent 7102and a compact tortuous vent tube 7104 which allows air/gas to flowfreely from the vent to the urine drainage lumen, but is tortuous enoughto prevent liquid flow to the vent. For example, vent tube portion 7104may be a tube with baffling, or mesh, in the inner lumen. The embodimentshown in FIG. 71 may or may not include a positive pressure tube—it isshown without a positive pressure tube. This embodiment may or may notinclude a valve.

FIG. 72 shows an embodiment of the barb area which includes vent 7202and vent tube 7204. In this embodiment, the vent tube is in fluidcommunication with positive pressure tube 7206, and vent 7202 is in linewith positive pressure lumen, so that fluid under positive pressurepasses through/across the vent and into the drainage lumen via opening7208. Vent tube 7204 is shown coiled here, to help prevent any back flowof urine into the vent tube, however, vent tube 7204 may be of anyconfiguration, including straight tubing, or a lumen built into the barbarea. Vent 7202 is shown here near the junction of vent tube 7204 andpositive pressure tube 7206, however, the vent may be anywhere along thepositive pressure lumen, including near the pump/cassette, or nearopening to the drainage lumen 7208. This embodiment may or may notinclude a valve.

FIGS. 73A and B show an embodiment of the barb area which includes vent7302 and a compact tortuous vent tube 7304 which allows air/gas to flowfreely from the vent to the urine drainage lumen, but is tortuous enoughto prevent liquid flow to the vent. In addition, the vent end of venttube 7304 may be configurable or bendable or deformable so that it canbe oriented upward after the barb area has been affixed to the patient'sleg. By orienting the vent end of the vent tube upward, the chance ofthe vent's exposure to liquid is reduced. For example, vent tube portion7304 may be essentially a flattened coil. The embodiment shown in FIG.73 may or may not include a positive pressure tube—it is shown without apositive pressure tube. This embodiment may or may not include valve7306.

FIG. 74 shows an embodiment of the barb area which includes multiplevents 7402 and optional valve 7404. The multiple vents reduce thechances of all the vents becoming wetted from urine. The multiple ventsmay be in any suitable configuration including a line, a circle, etc.The multiple vents may be on one side of the barb or may encircle thebarb partially or fully. For example, 2 vents may be includes, or forexample, 3 vents may be included, or for example, 4 vents may beincluded or for example, 5 vents may be included or for example, 6 ventsmay be included or for example, 7 vents may be included or for example,8 vents may be included or for example, 9 vents may be included or forexample, 10 vents may be included. The embodiment shown in FIG. 74 mayor may not include a positive pressure tube—it is shown without apositive pressure tube. This embodiment may or may not include a valve.

FIG. 75A shows an embodiment of the barb area which does not rely on avent, although it may still include one or more vents. In thisembodiment positive pressure tube 7502 is in fluid communication withthe urine drainage lumen via opening 7504. In addition, valve,preferably a pressure sensitive valve, 7506 is between opening 7504 andthe drainage catheter and in fluid communication with a positivepressure source via opening 7510. Valve 7506 is depicted in FIG. 75A asan inflatable valve, such as an annular balloon (also shown in FIG.75B). Valve 7506 may be inflated via the same pressure source which isconnected to positive pressure tube 7502 or a separate source. Valve7506 may be in fluid communication with the lumen of positive pressuretube 7502 as is shown here or may be inflated via a separate positivepressure lumen.

In this embodiment, valve 7506 closes when positive pressure isperiodically applied to the drainage lumen via positive pressure tube7502. The closing of the valve prevents air or positive pressure fromreaching the bladder and allows the positively pressurized fluid (gas orliquid) to purge the drainage lumen. When positive pressure in thepositive pressure tube is reduced, the valve is opened and urine isagain permitted to drain from the bladder. A slight positive pressuremay be maintained in the positive pressure tube to offset the negativepressure in the urine drainage line. If higher pressure is required toclear the line of airlocks, valve 7506 is closed for the duration of thehigher pressure flushing.

FIG. 76 shows an embodiment similar to that shown in FIG. 75, however inthis embodiment, valve 7602 is a passive mechanical valve. Valve 7602 isnormally in the flat, or open, position. When the positive pressure inthe positive pressure tube is higher than any negative pressure in thedrainage lumen, the valve automatically closes so that fluid/positivepressure is not transferred to the Foley catheter/bladder of thepatient.

Alternatively, a venturi may be used to control the negative andpositive pressures exuded on the barb area, similar to an automobilecarburetor.

FIGS. 77A and B show another embodiment which uses a more active valvesystem. This embodiment includes suction chamber 7702, compliant portion7704, patient-side valve 7706, drainage-side valve 7708, drainage lumeninlet 7710 and pressure lines 7712, 7714, 7716, 7718.

In the passive, or open, position, both patient-side valve 7706 anddrainage-side valve 7708 are open, i.e., the balloon/bladders are notinflated, so that urine may pass freely from the drainage catheter 7722,through the drainage lumen 7720 of the barb, and through the drainagetubing 7724. In the open position, compliant portion 7704 is in aneutral position. When a blockage event occurs, such as an airlock, orperiodically to prevent blockages, the drainage-side valve 7708 isclosed by applying pressure, such as pressurized fluid (gas or liquid)through pressure line 7716. Compliant portion 7704 is expanded byapplying negative pressure through pressure line 7718. Pressure line7714 remains neutral, or closed. Pressure line 7712 remains neutral, orclosed, or negative to completely deflate valve 7706. This configurationeffectively applies a negative pressure to the drainage catheter byexpanding compliant portion 7704 while closing off fluid flow todrainage line 7724. This configuration is shown in FIG. 77A.

The configuration of FIG. 77A lasts only a short time, for example forabout 0.5 to 1 seconds, or about 1-3 seconds, or about 3-5 seconds. Thenpatient-side valve 7706 is closed by applying positive pressure topressure line 7712 and drainage-side valve is opened by reducing thepressure in pressure line 7716 to neutral, or applying negative pressureto pressure line 7716. The volume of compliant portion 7704 is reducedby increasing the pressure in pressure line 7718 to neutral or applyingpositive pressure to pressure line 7718. Positive pressure may also beapplied to pressure line 7714. This configuration is shown in FIG. 77B.In this configuration, fluid in drain lumen 7720 and drainage line 7724is flushed with fluid (gas/liquid) through pressure line 7714 and/or bythe positive pressure applied by the reduction of volume of compliantportion 7704, effectively flushing the urine through the drainage line.After flushing, the system is brought back to a neutral position wherepatient-side valve 7706 and drainage-side valve 7708 are both open andcompliant portion 7704 is in a neutral position.

FIG. 78 shows an embodiment similar to that shown in FIG. 72, but with apositive pressure vent tube 7802, and not a separate vent tube. Vent7804 is in fluid communication with, and in line with, the lumen ofpositive pressure vent tube 7802. Vent 7804 is also in fluidcommunication with barb area of the urine drainage lumen 7808, and isconnected to area 7808 by opening 7806. Fluid/air/gas under positivepressure is passed across vent 7804, through opening 7806, and into area7808 which is in fluid communication with the drainage lumen. In otherwords, positively pressured fluid/air/gas passes across the filter tothe inside of the barb. The wetting of vent 7804 is prevented bycontrolling the positive pressure within the positive pressure tube, andacross vent 7804, as well as the negative pressure of the drainagelumen. In some embodiments, the pressure within the barb area of urinedrainage lumen 7808 is close to about zero. Vent 7804 may be anywherealong the length of positive pressure vent tube 7802. The embodimentshown in FIG. 78 may or may not include a one-way valve between thefilter and the opening. The positively pressurized fluid/air/gas may bepassed through the vent continuously, intermittently, sporadically, etc.The positively pressurized fluid/air/gas may be passed through the ventas a stream, or a puff or pulse.

FIG. 79 shows an embodiment where the area within the barb which is influid communication with the urine drainage lumen has a larger volume.Fluid 2902, such as urine, flows from the drainage catheter, into largereservoir 7904, and then into the urine drainage lumen. Reservoir 7904is large enough that it is unlikely to ever be filled completely withliquid. The volume of the reservoir which is not filled with liquid willbe filled with air or gas. One way valve 7908 may also be present. Sincereservoir 7904 always has some air/gas in it, vent 7906 may be situatedso that it is seldom in contact with the urine/fluid in the reservoir.In other words, the vent may be on the side of the bubble within thereservoir. More than one vent may be present to make sure that at leastone vent is always in fluid communication with the gas bubble within thereservoir. In some embodiments, the volume of reservoir 7904 may belarger than the volume of the inner lumen of the drainage tube.

FIGS. 80A and 80B show an embodiment in which the area of the vent isvery large. Vent 8002 is shown here to be a large flat circle or disc,however the vent may be any shape and size. The vent may be flat orcurved, such as to wrap around the barb area. The embodiment here isshown with one opening 8004 and a one-way valve 8006, however otherembodiments may have more than one opening and may or may not have avalve. Some embodiments may have a filter surface of greater than about1 cm2. Some embodiments may have a filter surface of greater than about2 cm2. Some embodiments may have a filter surface are of about 3 toabout 4 cm2. Alternatively, some embodiments may have a filter surfaceare of about 2 to about 4 cm2. Alternatively, some embodiments may havea filter surface are of about 4 to about 6 cm2. Alternatively, someembodiments may have a filter surface are of about 6 to about 10 cm2.

FIG. 81 shows an embodiment with a replaceable vent. Replaceable vent8102 is shown here in an embodiment with positive pressure tube 8104 andone-way valve 8106, however embodiments may also exist without thepositive pressure tube and/or valve. Replaceable vent 8102 may beremoved and replaced via an attachment mechanism such as a luer-lock, asnap lock, a slide-in lock, a press-fit, or any other suitablemechanism. Vent replacement may be performed periodically, such as onceper day, or as needed, for example when the controller alerts the userthat the vent is no longer working properly, or when the user noticesthat the vent is no long functioning. The vent may have a chemicalsensitive to urine or a component of urine which changes color toindicate that it has been wetted. For example, a pH sensitive, or otherchemical or attribute sensitive paper may be used in the replaceablevent which changes color and is visible to the user. The replaceablevents may be disposable.

FIGS. 82A and 82B show an embodiment where the filter is flexible. Inthis embodiment, filter 8202 may be flexible or deformable, i.e. it maybe convex/concave, or loose in its housing, the movement of flexiblefilter 8202 may help unclog the filter if it has been wetted orcontaminated. The movement of the filter may be controlled by positivepressure via positive pressure tube 8204, negative pressure via theurine drainage lumen, valve 8206, or any single or combination of theabove. Some embodiments may also include a mechanical mechanism toagitate, shake, vibrate, bend and/or move filter 8202. FIG. 82A, forexample, shows an example of an embodiment where negative pressure inthe urine drainage lumen causes the filter to be concave. FIG. 82B showsthe same example after positive pressure has been applied to the ventvia positive pressure tube 8204. The pressure within vent housing 8208may be controlled by the crack pressure of the one-way valve, or by therelative negative and positive pressures within the urine drainage lumenand the positive pressure tube. Similar embodiments may also exist wherethe filter is not flexible, but pressure is controlled within venthousing 8208 in a similar way which keeps the filter dry.

Alternatively, the filter (flexible or otherwise) may be wiped orscraped mechanically, either manually or automatically. Alternatively,the filter may include a chemical which inhibits protein adhesion and/orbuild-up, such as an enzymatic detergent. Alternatively, the filter mayinclude a chemical which inhibits biofilm, such as an antibacterialagent.

FIG. 83 shows an embodiment with multiple stacked filters. Filters ofdifferent pore sizes may be used in a stacked fashion. For example,courser pore filter 8304 may protect fine pore filter 8302 from wetting.Course pore filter 8304 may be placed between the fluid/urine and finepore filter 8302. In this configuration, liquid/urine would need to passcourser filter 8304 to contact fine filter 8302. More than 2 filters canbe stacked in this manner, either with graduated pore sizes, or similarpore sizes, or any pore sizes. For example, increasingly fine porefilters may be stacked so that the finer pore filters are further fromthe urine/liquid. Alternatively, one or more course pored filters, ofthe same or different pore size, may be placed between the urine/liquidand a fine pored filter. A one-way valve may or may not be present. Thepore size of courser pore filters 8304 may be around 10 microns.Alternatively, the pore size of courser pore filters 8304 may be around10 to around 20 microns. Alternatively, the pore size of courser porefilters 8304 may be around 10 to around 30 microns.

FIG. 84 shows an embodiment with continual positive pressure exerted onthe barb area by the fluid within the positive pressure tube. Positivepressure tube is under substantially constant positive pressure so thatfluid (preferably air/gas) is continually passing through opening 8404.The positive pressure exerted on the fluid in interior 8406 of the barbis controlled so that fluid does not backflow into the urine drainagecatheter. In other words, the negative pressure exerted on the fluid ininterior 8406 is always greater or about the same as the positivepressure exerted on the fluid in interior 8406. The positive pressuremay be controlled at the controller, and/or it may be controlled by thesize of opening 8404, for example, by sizing opening 8404 very small.For example, the diameter of opening 8404 may be less than about 1 mm.Alternatively, the diameter of opening 8404 may be less than about 2 mm.Alternatively, the diameter of opening 8404 may be less than about 3 mm.Alternatively, the diameter of opening 8404 may be less than about 4 mm

FIG. 85 shows an embodiment with an accordion shaped vent. Vent 8502 inthis embodiment is shaped like an accordion. The vent may be compressedin the direction of the double headed arrow. This compression may clearthe vent of clogs/wetting etc. The compression may be done manually,automatically/mechanically, and/or using pressure (negative and/orpositive) within the vent area.

FIG. 86 shows an embodiment with a single vent and multiple openings. Inthis embodiment, more than one small openings 8602 separate the urinedrainage lumen from vent 8604. The small openings prevent fluid fromcoming in contact with vent 8604. The multiple openings may serve asredundancy, so that if one or more openings become clogged, otheropenings remain open. The openings may also be used to control thepassage of air/gas/fluid through vent 8604—more holes result in lessresistance to air flow, fewer holes results in higher resistance to airflow.

Any of the embodiments herein may include physiological pressuremeasurements or they may be used without physiological pressuremeasurements. For example, the system shown in FIG. 67 through FIG. 86and other embodiments may not include the thermistor nor the pressurelumen and may be used with a standard Foley catheter.

In some embodiments, pressure may be measured at the positive pressuretube/drainage tube junction. Alternatively, the pressure may be measuredat the sensing Foley catheter/drainage tube junction, or in the area ofthe barb. Pressure may be measured at any of these locations byincorporating an additional tube or lumen, which is in fluidcommunication with the pressure tube/drainage tube junction, or with thearea of the barb at one end, and in fluid communication with a pressuresensor or transducer at the other end. For example, this pressuremeasuring lumen may be in fluid communication with the controller whichhouses a pressure sensor at one end (the sensor end), and in fluidcommunication with the positive pressure tube/drainage tube junction onthe other end (the sensing end). A pressure sensitive membrane may bepresent at the sensing end to prevent urine contamination of the lumen.

Airlocks may also be detected so that they can be optimally clearedand/or avoided. Using any of the embodiments herein, the controller mayapply a slight positive or negative pressure to the urine drainage lumenand sense the response. A dampened response may indicate the presence ofairlocks, a less dampened response may indicate fewer airlocks since airis more compressible than urine. If excessive airlocks are detected, thecontroller may initiate airlock clearing, for example by applyingnegative pressure to the drainage lumen.

The vent tube may be a separate tube from the drainage tube and may beinserted within the drainage lumen or even within the Foley catheter.FIG. 87 shows an embodiment of the sensing Foley catheter system wherethe vent tube is inside the urine drainage tube. This type of embodimenthas the advantage that it can be used with any standard drainage tube.The vent tube essentially places a vent anywhere within the drainagelumen, either within the drainage tube, or within the Foley catheter.The vent tube may be slidably inserted within the drainage tube and/orthe Foley catheter, and may be moved at any time.

In the embodiment shown in FIG. 87, vent tube 8704 may be open tovent/filter 8702 (which is open to atmospheric pressure) within thecollection reservoir at one end (the “air end” 8708), and open at theother end (the “urine end” 8710) which is within urine drainage lumen8706. Although the vent tube is shown here to terminate within the barbat the base of the Foley catheter, the vent tube may terminate anywherewithin the urine drainage lumen including anywhere within the drainagetube or within the Foley catheter. The vent tube may remain in onelocation, or may be moved within the system to maximize urine drainageand minimize airlocks and damage to the bladder caused by negativepressure within the bladder.

FIG. 88 shows another embodiment of the sensing Foley catheter systemwhere vent tube 8802 has vent/filter 8804 at the “urine end” of thetube, and is open to atmosphere on the “air end” 8806 of the tube. Theremay also be a filter/vent at both ends. The “air end” of the vent tubemay exit the drainage lumen via a y-arm adapter, a stopcock or otherstandard ways. The “air end” of the vent tube may exit the system fromwithin the collection vessel, via a channel or port incorporated intothe collection vessel. Again, the vent tube may be used with any urinedrainage tube including a standard urine drainage tube.

FIG. 89 shows an embodiment similar to that shown in FIG. 88 with theaddition of positive pressure tube 8902.

FIGS. 90 and 91 show the vent tube at different locations within thesensing Foley catheter system. In FIG. 90, the “urine end” 9002 of thevent tube is only part way within the drainage tube. For example thevent tube may be inserted through approximately half of the drainagetube. Or for example the vent tube may be inserted through approximatelyone third of the drainage tube. Or for example the vent tube may beinserted through approximately two thirds of the drainage tube. In FIG.91, the “urine end” 9002 of the vent tube is within the Foley catheter.The location of the “urine end” of the vent tube is determined based onmaximizing urine drainage and minimizing the effect of airlocks on thedrainage and minimizing negative pressure within the bladder.

The vent tube may incorporate one or more than one filter/vents. Thevent tube may incorporate one or more than one cutouts that are in fluidcommunication with the inner lumen of the vent tube, and which areultimately in fluid communication with a vent/filter, either in thecollection reservoir or elsewhere. The multiple filter/vents or multiplecutouts may be around, or along the vent tube or both. The vent tube mayinclude a UV light directed at the filter, at the “urine end”, orelsewhere, to maintain sterility.

FIGS. 92A and 92B show some possible embodiments of the drainage lumen,for example drainage lumen 1012 shown in FIG. 10A. FIG. 92A shows adrainage lumen with collapsible/expandable portion 9202. Portion 9202may be manufactured from a lower durometer material than the rest of thedrainage lumen, allowing it to collapse or expand depending on thepressure within. The lumen will collapse down to a lower internalarea/volume in lower or negative pressures and will expand with higheror positive pressures. Airlocks may be reduced by this change of lumenvolume at different pressures. This type of lumen may be incorporatedinto any of the embodiments herein.

FIG. 92B shows an embodiment of a drainage lumen which includes 2lumens. The inner lumen shown here is a negative pressure/urine drainagelumen 9204. The outer lumen is a positive pressure lumen 9206. Betweenthe two lumens are openings 9208. The openings may or may not include afilter membrane. The two lumens may be concentric, as shown here, oradjacent. Positive pressure lumen serves essentially the same role asthe positive pressure vent tube shown elsewhere herein. Eitherconstantly, or periodically, positive pressure is exerted on positivepressure lumen 9206 as negative pressure is exerted on drainage lumen9204, resulting in clearance of drainage lumen 9204.

FIGS. 93A through 93E show another embodiment of the drainage lumen.This embodiment also includes drainage lumen 9302 and positive pressurelumen 9304. In this embodiment, positive pressure lumen 9304 isexpandable and collapsible. In the positive pressure lumen's expandedstate, it partially or fully blocks the drainage lumen. In the positivepressure lumen's collapsed state, the drainage lumen is substantiallyopen allowing fluid to flow freely through the drainage lumen. FIG. 93Ashows the drainage lumen in the closed state near the patient side ofthe drainage tube. FIG. 93B shows the drainage lumen in the closed statefurther from the patient. FIG. 93C shows the drainage lumen in the openstate.

FIG. 93D shows a longitudinal view of the drainage tubing in the closedstate. FIG. 93E shows a longitudinal view of the drainage tubing in theopen state. In the open state, as shown in FIGS. 93C and 93E, positivepressure lumen 9304 as collapsed and does not substantially obstructdrainage lumen 9302, allowing urine to flow freely from the body to thereservoir. When airlock or other blockage clearance of the drainage tubeis performed, the positive pressure lumen is inflated to urge theurine/liquid down the drainage tube toward the collection reservoir. Thepatient end 9306 of the positive pressure lumen may be of a largerdiameter and/or a lower durometer than the reservoir end 9308 of thepositive pressure lumen. This allows the patient end of the positivepressure lumen to inflate before the reservoir end inflates. In thisway, the drainage lumen is blocked first nearest the patient, and thenthe either substantially all of the drainage lumen is filled or part ofthe drainage lumen is filled with the inflation of the remainder of thepositive pressure lumen. The positive pressure lumen may be inflated ateither the patient end or the reservoir end of the drainage tube. One ormore filters may be present along the length of the drainage lumen.

Embodiments of the sensing Foley catheter system may include the abilityto measure pressure within the bladder via a pressure balloon connectedto the Foley catheter, or via a pressure balloon or other pressuresensor inserted within the drainage lumen of the drain tube and/or theFoley catheter. For example, see FIGS. 94A-94C.

FIGS. 94A-94C show embodiments of the sensing Foley catheter systemwhere the pressure sensor is in fluid communication with the urine lumenof a Foley catheter, but may reside on a separate catheter. Foley typecatheter 9402 is shown with urine lumen 9404 and urine drainage opening9406. Small pressure sensing catheter 9408 with pressure sensing balloon9410 is shown inside the urine drainage lumen of the Foley typecatheter. The outer diameter of the pressure sensing catheter is smallenough so that it fits within the urine drainage lumen of a Foley typecatheter. For example the outer diameter of the pressure sensingcatheter may be less than about 4 mm, alternatively the outer diameterof the pressure sensing catheter may be less than about 3 mm,alternatively the outer diameter of the pressure sensing catheter may beless than about 2 mm, alternatively the outer diameter of the pressuresensing catheter may be less than about 1 mm.

The pressure sensor on the pressure sensing catheter may be near thedistal end of the pressure sensing catheter, or it may be anywhere alongthe length of the catheter. The pressure sensor may be a pressuresensing balloon, or it may be any type of pressure sensor, such as apiezoelectric sensor, a mechanical sensor, etc. In the case of apressure sensing balloon, the inflated balloon may be smaller than theinner diameter of the urine drainage lumen of the Foley type catheter,or the inflated balloon may be large enough to fill the urine drainagelumen of the Foley type catheter.

The inflated pressure sensing balloon may fill the urine drainage lumenof the Foley type catheter allowing for better pressure measurements.The pressure sensing balloon may be periodically deflated or partiallydeflated to allow urine to flow from the bladder through the Foley typecatheter. The controlling of the pressure sensing balloon inflationcycle may be controlled by the controller of the present invention.

FIG. 94B shows an embodiment of the pressure sensing catheter which hasboth occluding balloon 9424, and pressure sensing balloon 9426. Theoccluding balloon occludes the urine drainage lumen so that the pressuresensing catheter is only sensing pressures between the occluding balloonand the bladder, which may more accurately and precisely measure thepressures within the bladder.

The outer diameter of the inflated pressure sensing balloon may less bethan about 5 mm, alternatively the outer diameter of the pressuresensing catheter may be less than about 4 mm, alternatively the outerdiameter of the pressure sensing catheter may be less than about 3 mm,alternatively the outer diameter of the pressure sensing catheter may beless than about 2 mm, alternatively the outer diameter of the pressuresensing catheter may be less than about 1 mm.

FIG. 94C shows a standard Foley type catheter with retention balloon9412, urine drainage opening 9406, retention balloon port 9414, andurine drainage port 9416. Adapter 9418 is shown connected to urinedrainage port 9416. Adapter 9418 has two ports, urine drainage port 9420and secondary urine lumen port 9422. Pressure sensing catheter 9408 isshown in urine lumen port 9422. In this way the pressure sensingcatheter is in fluid communication with the urine drainage lumen of theFoley type catheter. Proximal end of pressure sensing catheter 9408 isconnected to a pressure sensor such as a pressure transducer, similar toother embodiments herein. Pressure sensing catheter 9408 may have only asingle lumen, the sensing balloon lumen, or it may contain other lumens.In the case where the pressure sensor of the pressure sensing catheteris a mechanical pressure sensor, the pressure sensing catheter may haveno lumens, or the pressure sensing catheter may have a balloon forsealing the urine drainage lumen of the Foley type catheter.

The pressure sensing catheter may also be inserted through the urinedrainage lumen of the drainage tube.

Pressure measurements can be taken over time using the pressure sensingcatheter and analyzed in any of the ways disclosed herein. To improvepressure measurements, drainage port 9420 may be periodically closed orblocked. Blocking of drainage port 9420 may be done mechanically, with astopcock or valve, or automatically, for example with a solenoid valveconnected to the controller. An advantage of this embodiment is thatpressure sensing catheter 9408 can be used with any Foley type catheterto measure pressure. In addition, pressure sensing catheter 9408 can beinserted and removed from a Foley type catheter after the Foley typecatheter is already in place in the patient's bladder.

The pressure sensing catheter may be combined with the vent tube shownin other figures. In this way, the pressure sensing, urine drainage,anti-airlock, venting components of the sensing Foley catheter systemcan be used with any standard Foley catheter and drainage tube.Alternatively, a pressure sensing catheter/vent tube combination may beused with a more specialized Foley catheter and/or drainage tube.

In any of the embodiments that include any type of airlock clearingmechanism, the air-lock clearing may be performed continuously,periodically, on demand, or when an airlock condition is sensed. Theairlock clearing mechanism prevents or reduces airlocks. For example,the airlock clearing mechanism may reduce airlocks such that airlocksare cleared at least every 60 minutes. Alternatively, airlocks may becleared at least every 45 minutes. Alternatively, airlocks may becleared at least every 30 minutes. Alternatively, airlocks may becleared at least every 20 minutes. Alternatively, airlocks may becleared at least every 10 minutes. Alternatively, airlocks may becleared at least every 5 minutes. Alternatively, airlocks may be clearedat least every 1 minute.

In any of the embodiments that include a vent or filter or vent tube aspart of the barb area or drainage tube, fluid (i.e. urine) drainage maybe discontinuous, i.e. interrupted, because of gas/air introduced intothe drainage lumen via the vent/filter/vent tube. In other words, thedrainage lumen may alternate liquid (i.e. urine) and gas.

In any of the embodiments that include measuring urine output volume inreal time, real time may mean urine output volume measurements reportedare accurate to within about 1 minute. Alternatively, real time may meanurine output volume measurements reported are accurate to within about 5minutes. Alternatively, real time may mean urine output volumemeasurements reported are accurate to within about 10 minutes.Alternatively, real time may mean urine output volume measurementsreported are accurate to within about 20 minutes. Alternatively, realtime may mean urine output volume measurements reported are accurate towithin about 30 minutes. Alternatively, real time may mean urine outputvolume measurements reported are accurate to within about 60 minutes.

Bubbles in Urine—Prevent Bubbles and/or Prevent Impact on Measurements

On occasion protein, or other components, in the urine may causeexcessive bubbling in the urine within the drainage lumen and/or thecollection vessel which may cause problems such as wetting of thevent/filter(s), urine entering the overflow area of the collectionvessel, inaccurate measurements etc. Some embodiments of the sensingFoley catheter system incorporate anti-bubble mechanisms.

In some embodiments, such as those that incorporate a positive pressuretube, precise control of the pressure within the urine drainage can beobtained. It is possible to occasionally exert a slight positivepressure within the drainage system (i.e. the drainage lumen and/or thecollection chamber) to collapse any bubbles which are present or toprevent bubble from forming.

A surfactant, such as silicone, may be added to the system. For example,a slow dissolving silicone capsule may be added to the collectionreservoir. Alternatively a surfactant coating may be used on the insideof the drainage lumen and/or the inside of the collection vessel.

Bubble may be eliminated or reduced at the junction of the drain tubingand the collection vessel. Some embodiments are shown in FIGS. 95A-C.For example, the base of the drainage tubing may be S-drain shaped (asin the drain under a sink), the inner diameter of the drainage tubingmay expand near the junction with the collection vessel, or elsewhere.The drainage tubing may be bulb shaped or cone shaped. The drain lumenmay become annularly shaped, as is shown in FIG. 95C. In thisembodiment, the fluid is forced to flow down the side of a slanted conesurface to reduce bubbles, similar to how beer is poured down the sideof a glass instead of into the center of a glass to reduce beer foam.The bubble reducing feature is shown here at the base of the drainagetube, but may be in any part of the drainage tube or the system. In someembodiments, the drainage lumen may be flattened, again to force theurine in contact with surfaces. For example, the urine drainage lumenmay flatten down to less than about 1 mm. The urine drainage lumen mayflatten down to less than about 2 mm. The urine drainage lumen mayflatten down to less than about 3 mm.

Urine may also be forced to flow to a point, as is shown with theinverse cone embodiment in FIG. 96A. The cone may have angles as shownhere, or may be more curved. The cone shape generally transitions from asmall to large area, and/or from a large to a small area. This and otherbubble reducing mechanisms may also be within the collection vessel. Forexample as is shown in FIGS. 96B-D, an angled baffle may be incorporatedinto the collection reservoir to force the fluid down an angled surface.The angled surface may extend all the way to the bottom of thecollection vessel or only partially into the collection vessel.Different angles may be used, for example, angles from about 10 degreesto angles of about 80 degrees.

Angled baffles, as shown by embodiments in FIG. 96C and FIG. 96D mayalso be preferred to improve the accuracy of urine volume measurement,especially under critical care conditions where the patient has lowurine output and continuous measurement of urine output (ml/min orml/sec) is desired to diagnose patient's vulnerability for the onset ofAKI, sepsis, or other conditions. Accurate measurement of small urinevolumes is better measured in a conical or angled baffle, due thegreater height of the urine column, for a given urine volume, comparedto a flat-bottomed baffle or cassette. The ultrasonic transducer orsimilar transducers on the controller can more reliably measure heightand provide an accurate measure of urine volume and rate of urineoutput, especially when the patient's kidney is injured and makes littleurine. In addition, an angled/baffle or cassette (urine collectionchamber) may be less sensitive to changes in the tilt angle of thecontroller and reduce measurement error, compared to a flat surfacedcassette, for small urine volumes.

FIG. 97A shows an embodiment of the sensing Foley catheter system wherethe drainage lumen extends into the collection vessel/cassette so thatthe fluid generally drains into the collected fluid below the fluidlevel. The drainage end of the drainage lumen may be cut at an angle toprevent the tubing from abutting the bottom of the cassette which mayblock fluid flow. The angle cut 9724 may be about 45 degrees, about10-80 degrees or any suitable angle. Other shapes may be used at thedrainage end of the drainage lumen to achieve the same result. Forexample, FIG. 97B shows a drainage lumen, the tubing of which iscastellated at the drainage end. Castellations 9726 may be of any shapeinclude rounded, rectangular, triangular, scalloped, etc.

FIG. 97C shows an embodiment of the sensing Foley catheter system wherethe drainage lumen extends into the cassette, and includes a flattenedarea 9728. In this embodiment the cross sectional area of the drainagelumen may stay the same, increase or decrease in the flattened area,however preferably at least one dimension increases to force increasedsurface area contact with the fluid flow. The flattened area may directflow downward, as is shown in FIG. 97C, or the flattened portion may beangled to force fluid to flow in contact with at least one side of thelumen's interior surface. Alternatively, or in addition, an angledbaffle, such as baffle 9730 shown in FIG. 97D may be used. The angle ofbaffle 9730 may be about 45 degrees, about 10-80 degrees or any suitableangle. The angled baffle, or flattened area, may be used with any of thedrainage tubing/lumen designs shown herein.

FIG. 98A shows an embodiment of the sensing Foley catheter system wherethe drainage lumen area increases and decreases. Bulb 9832 may beincorporated into the drainage tubing above the cassette, within thecassette, as is shown in FIG. 98D, or anywhere along the drainage lumen.The area above and below the bulb may be essentially identical, or thearea below the bulb may be less than the area above the bulb as shown inFIG. 98B. Reduced drainage lumen area portion 9834 may be relativelyshort, for example portion 9834 may be about 1 mm-10 mm long.Alternatively portion 9834 may be about 10 mm-20 mm long. Alternativelyportion 9834 may be about 10 mm long. FIG. 98C shows an embodiment wherenarrowed section 9836 includes more than one reduced area fluid drainagelumens. This allows increased surface contact of the drainage lumenwithout significantly reducing the area of the drainage lumen. Narrowedsection 9836 may be used in conjunction with bulb 9832 or without thebulb.

Note that any of the bubble reduction embodiments enclosed herein may beused anywhere in the drainage lumen, including the drainage tubingoutside the cassette, and drainage tubing/lumen within the cassette. Forexample, FIG. 98D shows an embodiment similar to that shown in FIG. 98Bwhere the bulb is within the cassette.

FIG. 99A shows an embodiment of the sensing Foley catheter system whereat least part of the drainage lumen is rough to cause bubbles todisperse and/or pop.

FIGS. 99B and 99C show another bubble reducing embodiment. In thisembodiment a grate, or honeycomb, or mesh is inside the base of thedrainage tube. The mesh helps to break up bubbles and may beperiodically compressed to clear the area of fluid and also to helpbreak down the bubbles.

Alternatively, or in addition, a flat mesh may be inserted anywherewithin the system, for example at the drainage tube/collection vesseljunction.

In some embodiments the cassette and/or drainage lumen may be vibratedeither continuously or intermittently to break up bubbles.

FIGS. 100A-C show embodiments which incorporate a plate, floating ornon-floating, to compress or break up the bubbles at or near the surfaceof the urine in the collection vessel. The plate may simply float on thesurface and passively raise and fall with the volume of urine in thevessel, or the plate may be actively moved up and down. The plate mayalso be fixed in place. The plate may be porous or solid. In embodimentswhere the plate is on the surface of the fluid, the plate may also beused for urine output measurements. The location of the plate may beidentified by ultrasound, visual means (as in a camera), laser or othertechniques. The volume of the fluid within the collection vessel can bedetermined directly from the level of the fluid, which can be determinedby the location of the plate.

The interior of the cassette may be rectangular, or shaped otherwise.For example, the sides of the interior of the cassette may taper inwardtoward the bottom so that there is a larger top surface of urine withrespect to the volume of urine in the cassette. This may result in moreaccurate urine volume measurements at smaller volumes.

Some embodiments may include a volumetric baffle at a set volume mark,for example at 50 ml. This volumetric baffle may be similar to baffle2302 shown in FIG. 23, except that it will be at a predetermined volumelocation. When the top surface of the urine volume in the cassette is ator near the volumetric baffle, an ultrasonic signal is stronger than itwould be otherwise. For example, the volumetric baffle may be positionedso that when the top surface of the volume of urine is at about 50 ml(or other set volume), the top surface of the urine volume will be at ornear the volumetric baffle. As the two surfaces (urine and volumetricbaffle) approach each other or touch each other, the ultrasonic signalis strongest.

FIG. 101A shows an embodiment of the sensing Foley catheter system whichincludes valves at both the drainage ports 10102, and at the entry point10104, where the drainage tubing connects to the collection vessel. Thisallows the controller to periodically pressurize the collection vesselwhich may reduce bubbles. This may also result in more accuratemeasurements of urine output since urine flow into the collection vesselcan be stopped by the controller during urine emptying.

FIG. 101B shows an embodiment of the collection vessel where the urineoverflow path is made more long and/or convoluted/tortuous and/ornarrow. This configuration makes it more difficult for bubbles to flowinto the overflow path resulting in inaccurate measurements of urineoutput. The overflow path may include one or more path angles which aregreater than 45 degrees.

Some embodiments include a drainage tube with a small inner lumendiameter. For example, in some embodiments, the inner lumen diameter isabout 2 mm In some embodiments, the inner lumen diameter is about 1 mmIn some embodiments, the inner lumen diameter is about 3 mm In someembodiments, the inner lumen diameter is less than about 2 mm in someembodiments the inner lumen diameter is less than about 1 mm In someembodiments the inner lumen diameter is less than about 3 mm.

In some embodiments, drained urine can be used to “wash” the bubbleswithin the drainage tube or collection reservoir. Urine can be cycledback into the drainage tube to increase the volume within the drainagetube and help “wash” bubbles in the tubing and/or reservoir. Thecontroller compensates for the recycled urine in calculating the urineoutput volumes.

In some embodiments, pressurized air may be introduced into the drainagetube and/or the collection vessel. The forced air pops and/or compressesthe bubbles and also forces the urine up against the surfaces of thesystem to decrease bubble formation. The cross sectional area of thedrainage tube may decrease, stay the same or increase as the drainagetube transitions into the flattened portion.

Leveling

In embodiments where urine volume is measured within the collectionvessel using ultrasound, it is important that the ultrasonic waves havea surface (i.e. the surface of the volume of urine) which isapproximately 90 degrees from the ultrasonic sensor. If the system istilted even a few degrees, the ultrasonic sensor may not be able tosense the surface of the urine and therefore may not obtain accuratemeasurements of urine volume. To compensate for this, the collectionvessel or base/controller may be attached to the bed via a self levelingattachment, for example, an attachment which is on a roller so thatgravity automatically levels the base when it is attached.

In some embodiments, slight angles in the system are handled by creatinga “rough” surface on the urine volume within the collection reservoir. A“rough” surface provides multiple angles for ultrasonic reflection, someof which will be approximately 90 degrees from the ultrasonicsensor/transducer. Roughness may be created by bubbling the urine usingair or other gas, by vibrating the collection reservoir and/or urine.Vibration can be achieved mechanically, ultrasonically etc. A floatingplate which floats on the surface of the urine may be used which has arough lower surface, concave lower surface or convex lower surface.Floating beads may be in the reservoir that are too large in diameter toexit the reservoir when the urine is drained, so that they remain in thereservoir as urine drains. A mesh, narrowing, small diameter opening orother mechanism may be used to prevent the beads from entering theoverflow area. In addition, as described above, angled baffles or anglewalled or tapered walled cassettes (or urine collection chambers) mayalso be used to accurately measure urine volumes.

Pressure Balloon Priming

Very small volumes of air or fluid may be necessary to adjust thepressure of the pressure balloon to prime it for optimal pressuresensing measurements. Because of this, an air/gas/fluid restrictor maybe utilized between the priming fluid and the pressure balloon. Therestrictor allows the priming pump to operate with smaller volumes ofair for more precise pressure balloon priming. The restrictor mayinclude a foam insert, a narrowing of the fluid lumen, or any othersuitable restrictor.

General Improvements

In some embodiments, a sensor on the bed, patient, within the sensingFoley catheter system or elsewhere senses when the patient is supine ornot supine. Pressure measured within the bladder will increase when thepatient is not supine and may adversely affect the data for analysis bythe controller. As a result, the controller may ignore pressure datacollected while the patient is not supine, or stop collecting pressuredata during this time. Alternatively, the pressure measurementsthemselves may be used to sense when a patient is not supine. A sharpincrease in pressure or an increase above a certain threshold mayindicate that the patient is sitting up, moving, coughing etc. Differentpressure profiles may indicate different events. Patient rolling toprevent bed sores may be tracked in this manner.

In some embodiments, an EKG measurement, either obtained through leadsattached to the sensing Foley catheter system or obtained independently,are used to sync the heart beats measured via the heart rate in thebladder with the EKG.

In some embodiments, the angle of the bed may be used by the controlleras an input parameter to results of calculations such as IAP or APP. Forexample, increasing the body angle (raising the head level of thepatient) will result in increased IAP. This increase may be differentfor healthier patients than for less healthy patients. As a result,determining the IAP at different bed angles may provide additionalinformation regarding the patient's health. Also, IAP may be lowered bydecreasing the head level which may temporarily stabilize a patient withhigh IAP.

In some embodiments the sensing Foley catheter will have at least onepressure sensor or lumen in fluid communication with an externalpressure sensor. This pressure sensor will allow for rapid, or highfrequency, sensing of pressure within the lumen (ideally faster than 1Hz) to allow for monitoring of physiologic signals within the lumen. Insome embodiments, the pressure lumen may be manually or automaticallypressurized and/or depressurized while pressure is monitoredcontinuously or intermittently. In embodiments where the pressure lumenincludes a pressure balloon, the balloon may be inflated and/or deflatedwhile pressure exerted by the body on the pressure balloon is monitored.The pressure lumen is able to transmit the pressure waves from the bodylumen, one of which is the cardiac pulsation generated by the inflow ofblood to the luminal organ and/or surrounding tissues. The pulsatilepressure from the cardiac pulsation and/or respiratory excursions can beused to determine pulmonary and cardiovascular pressures. In addition,the pressure in the pressure lumen/balloon may be increased above athreshold (i.e. 100 mmHg) and then slowly decreased through the sensingrange to determine the origin point of pulse pressure, extinction pointof pulse pressure, and/or relative increase/decrease in pressure pulsesize. The origin/extinction or relative increase/decrease in thepressure pulsations detected by the pressure sensor can be correlated tothe blood pressure, perfusion pressure, mean arterial pressure, strokevolume, stroke volume variability, respiratory effort, pulmonarypressure transmission and other pulmonary, gastrointestinal, renal orcardiovascular parameters. This process may be similar to a bloodpressure cuff, where the pressure is increased in the cuff above theblood pressure, and then the pressure in the cuff is slowly decreaseduntil the blood pressure waveforms (heart beat) either appear ordisappear.

FIG. 102 illustrates the pressure waveform and its extinction as thepressure balloon inflates. Note that above the mean arterial pressurethe cardiac pulsations are diminished and/or extinguished. With enoughdata to correlate the degree of extinction at relative pressure pointsto the mean arterial pressure, the mean arterial pressure can be derivedfrom this relative pressure waveform. The same can be used for pulmonarypressures and other pressures that can sensed within the lumens of thebody.

In some embodiments the pressure sensor/lumen is a capsule, or balloon,or reservoir, that can be inflated or filled slowly while pressure isbeing monitored using an external transducer. In some embodiments thepressure sensor is associated with a urinary catheter, such as a Foleycatheter. Alternatively the pressure sensor may be associated with anasogastric, orogastric or rectal tube. In yet further embodiments, thepressure sensor device and associated pressure-increasing device may befully implantable. In the tissue perfusion embodiment the pressuresensing may be inflated in the urethra or against the luminal surfaceand pulse oximetry may be performed to detect the blanching and/orperfusion of the luminal tissues at each pressure to determine thetissue perfusion pressure.

In some embodiments the catheter can use multiple measured parameterssynergistically in order to improve the quality of data analysis. In oneembodiment, the catheter has incorporated sensors for capturing an ECGsignal internally, such as via the urethra or bladder, or externally,such as via sensors placed on the legs or hips. Using this signal, theother measured parameters in synchrony with the cardiac cycle (such asstroke volume) can be synced with the electrical signal and noise can beremoved by taking the mean or median signal from many individualsamples. In another embodiment, the respiratory signal is used to guidewhich cardiac pressure signals should be used for stroke volumevariability analysis, by waiting for a model waveform to appear beforeperforming the analysis.

FIG. 103 illustrates a method of syncing cardiogenic signals (such aspressure fluctuations in the bladder caused by the pulse of the nearbyabdominal aorta) in order to obtain a clean signal for analysis. When anECG is captured in synchrony with another cardiac signal of interest,individual samples can be synced using, for example, the R-wave of theECG. In this figure, multiple pressure samples are captured and thenoverlaid, using the R-wave of the ECG for alignment. The median signalis then calculated by taking the median value of all pressure samples atthe same time during the cardiac cycle. The mean could also be used. Inthis manner, random noise is filtered out, as an extraneously high valuedue to noise in one sample will be canceled out by a similarlyextraneously low value in another. As more data points are added, theunderlying signal becomes stronger and can be used for analysis. Forexample, in the pressure signal shown, the peak-to-peak amplitude of thesignal can be used to derive relative stroke volume.

FIG. 104 illustrates a method of using the respiratory pressure signalto inform the cardiac pressure signal analysis in order to determinestroke volume variability (SVV). This method is particularly valuable innon-ventilated patients, i.e., patients not on a ventilator. Existingtechniques for measuring stroke volume, such as thermodilution or pulsecontour analysis, are limited in their ability to perform measurementsof stroke volume variability (variability of stroke volume betweeninspiration and exhalation) because they are blind to the respiratorycycle. Using luminal pressure as described herein, such as with a Foleycatheter in the bladder, is advantageous in that it allows forsimultaneous capture of respiratory and cardiac signals (as well asslower moving intra-abdominal pressure). In this manner, this presentdevice can discriminately choose which respiratory cycles to use foranalysis of stroke volume variability, as certain characteristics aremore suitable for proper analysis (such as the speed and size of thebreath). In this figure, a sample pressure signal captured from thebladder is shown. In the raw pressure signal on top, large fluctuationsare due to respirations, and are chosen for analysis based on the width,amplitude, or peak value of the wave, for example. Other characteristicsnot shown may also be used to define a suitable wave, including slope,area under the curve, shape, frequency, patterns, or repeatability etc.A curve amplitude filter may be used, where curves with an amplitudeabove a certain value are used, and those below the same, or anothercertain value are not used in the SVV calculation. The bottom figureshows the same signal after being passed through high- and low-passfilters. The high-pass filter leaves the underlying cardiac signal(dashed), and the low-pass filter leaves the underlying respiratorysignal (solid). In this example, the difference in strength of thecardiac signal (such as peak-to-peak value) between the peak and valleyof the respiratory signal can be used to calculate stroke volumevariability.

Respiratory rate and other parameters may be sensed via the SensingFoley catheter or may be sensed or obtained by any conventional ornon-conventional means. Other parameters that may be collected includetidal volume, spirometry, respiratory flow parameters, data collectedvia spirometry, expiratory effort, inspiratory effort etc. Any of theseparameters may be used to help in calculating stroke volume variabilityand/or other cardiac parameters.

The filter used to determine which pressure peaks are used in the SVVcalculation may be based on any of the pressure curve parametersdisclosed here. In addition, the SVV calculation itself may be used todetermine which pressure curve peaks are used in the calculation. Forexample, SVV is usually within around 10%. The system disclosed hereinmay include or exclude pressure curve data based on the resulting SVVcalculation being within a certain value range, such as about 10%.

The SVV calculation may also be patient specific. For example, apressure curve peak filter may be based on amplitude, but the cutoffamplitude may be patient specific and based on the average, mean, orother parameter of the pressure curve for that patient. Alternatively,the filter may be based on multiple patients, or multiple patientswithin a certain category, such as a certain disease state.

The signals and/or SVV calculation may also filter for patient movementsand/or other artifacts, such as coughing, shifting, sneezing etc.

In addition, a calculated result of a very low, or non-existent SVV maybe an indication of fluid overload, and appropriate treatment may beindicated.

In some embodiments of the disclosed system, the patient may be promptedto breath in a particular manner. For example, based on the pressurecurve shape (peak amplitude, frequency, etc.) the system may prompt thepatient to breathe more deeply, breathe more slowly, breathe normally,etc. The resulting respiratory pressure curve can then be factored intothe SVV calculation. This type of prompting may be performed by thesystem when the pressure curve is inadequate to provide a SVVcalculation, or for any other reason.

What is claimed is:
 1. A drainage assembly configured to preventnegative pressure build-up, comprising: an elongate catheter having afirst end configured for insertion within a body lumen, the catheterhaving at least one opening near or at the first end in fluidcommunication with a catheter lumen defined therethrough; a drainagetube having a drainage lumen in fluid communication with a second end ofthe catheter; a rigid cassette configured to fit into a cassette mountand which is in fluid communication with the drainage lumen; a drainagevalve located at an entry point where the drainage lumen connects to thecassette; a venting mechanism in fluid communication with the drainagelumen; a second valve positioned within the venting mechanism andconfigured to maintain a closed position until a first pressure levelwithin the drainage lumen drops to a second pressure level such that thesecond valve moves to an open position; a vent positioned in fluidcommunication with the second valve, wherein the venting mechanism isconfigured to inhibit wetting of the vent from fluid within the drainagelumen; and a controller in communication with the cassette, wherein thecontroller is configured to determine a fluid volume collected withinthe cassette.
 2. The assembly of claim 1 wherein movement of the secondvalve from the closed position to the open position introduces a gasfrom the venting mechanism and into the drainage lumen for clearing anyobstructions.
 3. The assembly of claim 1 wherein the venting mechanismcomprises one or more filters which are in communication with the secondvalve.
 4. The assembly of claim 1 wherein the vent is positioned at aremote end of the vent tube.
 5. The assembly of claim 4 wherein the venttube has a length of over 2 cm.
 6. The assembly of claim 4 wherein thevent tube is bendable or deformable.
 7. The assembly of claim 1 whereinthe vent is removably securable from the venting mechanism.
 8. Theassembly of claim 1 further comprising a pump configured to provide anegative pressure in the drainage lumen.
 9. The assembly of claim 1wherein the second pressure level is periodically or continually betweenabout −5 mmHg to −30 mmHg.
 10. The assembly of claim 1 wherein the ventcomprises a filter.
 11. The assembly of claim 1 wherein the second valveis positioned between an opening of the drainage lumen and the vent. 12.The assembly of claim 1 wherein the second valve comprises a passivemechanism.
 13. The assembly of claim 1 wherein the draining valvecomprises a passive mechanism.
 14. The assembly of claim 1 wherein thevent tube is in fluid communication with atmosphere.
 15. The assembly ofclaim 1 wherein the vent tube has a length of over 4 cm.
 16. Theassembly of claim 1 wherein the vent tube has a length of over 10 cm.17. The assembly of claim 1 wherein the cassette defines a tortuous flowpath within the cassette.
 18. The assembly of claim 1 where thecontroller is configured to apply the negative pressure periodically.19. The assembly of claim 18 wherein the controller is configured toapply the negative pressure at least every 60 minutes.
 20. The assemblyof claim 18 wherein the controller is configured to apply the negativepressure at least every 20 minutes.
 21. The assembly of claim 1 whereinthe vent tube has a length which extends with the drainage lumen fromthe venting mechanism.
 22. The assembly of claim 1 further comprising acamera in communication with the controller such that the camera isconfigurable to determine the fluid volume collected within thecassette.
 23. The assembly of claim 1 further comprising a pressuresensor in communication with the controller such that the pressuresensor is configurable to determine the fluid volume collected withinthe cassette.
 24. The assembly of claim 1 further comprising anultrasound sensor in communication with the controller such that theultrasound sensor is configurable to determine the fluid volumecollected within the cassette.
 25. A drainage assembly configured toprevent negative pressure build-up, comprising: an elongate catheterhaving a first end configured for insertion within a body lumen, thecatheter having at least one opening near or at the first end in fluidcommunication with a catheter lumen defined therethrough; a drainagetube having a drainage lumen in fluid communication with a second end ofthe catheter; a rigid cassette configured to fit into a cassette mountand which is in fluid communication with the drainage lumen, a drainagevalve located at an entry point where the drainage lumen connects to thecassette; a venting mechanism coupled to the drainage lumen, wherein theventing mechanism includes a vent tube and wherein the venting mechanismis configured to inhibit wetting of a vent from a fluid within thedrainage lumen; a controller in communication with the cassette, whereinthe controller is configured to determine a fluid volume collectedwithin the cassette; and a second valve configurable between a closedposition and an open position, wherein the controller is configured toapply a negative pressure to the drainage lumen such that the secondvalve moves from the closed position to the open position when a firstpressure level imparted upon the second valve is dropped by thecontroller to a second pressure level.
 26. The assembly of claim 25further comprising an overflow area, wherein the overflow area isconfigured to drain fluid from the cassette when excess fluid entersinto the cassette.
 27. The assembly of claim 25 wherein the ventingmechanism comprises one or more filters which are in communication withthe second valve.
 28. The assembly of claim 25 wherein the vent ispositioned at a remote end of the vent tube.
 29. The assembly of claim25 wherein the vent tube has a length of over 2 cm.
 30. The assembly ofclaim 25 wherein the vent tube is bendable or deformable.
 31. Theassembly of claim 25 wherein the vent which is removably securable fromthe venting mechanism.
 32. The assembly of claim 25 wherein the ventcomprises a filter.
 33. The assembly of claim 25 wherein the secondvalve comprises a passive mechanism.
 34. The assembly of claim 25wherein the drainage valve comprises a passive mechanism.
 35. Theassembly of claim 25 wherein the vent tube is in fluid communicationwith atmosphere.
 36. The assembly of claim 25 wherein the vent tube hasa length of over 4 cm.
 37. The assembly of claim 25 wherein the venttube has a length of over 10 cm.
 38. The assembly of claim 25 whereinthe cassette defines a tortuous flow path within the cassette.
 39. Theassembly of claim 25 further comprising a pump configured to provide anegative pressure within the drainage lumen.
 40. The assembly of claim25 wherein the second pressure level is periodically or continuallybetween about −5 mmHg to −30 mmHg.
 41. The assembly of claim 25 wherethe controller is configured to apply the negative pressureperiodically.
 42. The assembly of claim 41 wherein the controller isconfigured to apply the negative pressure at least every 60 minutes. 43.The assembly of claim 41 wherein the controller is configured to applythe negative pressure at least every 20 minutes.
 44. The assembly ofclaim 25 wherein the vent tube has a length which extends with thedrainage lumen from the venting mechanism.
 45. The assembly of claim 25further comprising a camera in communication with the controller suchthat the camera is configurable to determine the fluid volume collectedwithin the cassette.
 46. The assembly of claim 25 further comprising apressure sensor in communication with the controller such that thepressure sensor is configurable to determine the fluid volume collectedwithin the cassette.
 47. The assembly of claim 25 further comprising anultrasound sensor in communication with the controller such that theultrasound sensor is configurable to determine the fluid volumecollected within the cassette.